

InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
801. |
If the expression (px3 + x2 – 2x – q) is divisible by (x – 1) and (x + 1), then the values of p and q respectively are ?(a) 2, – 1 (b) –2, 1 (c) –2, –1 (d) 2, 1 |
Answer» (d) 2, 1 px3 + x2 – 2x – q is divisible by (x – 1) and (x + 1) ⇒ p(1)3 + (1)2 – 2(1) – q = 0 ⇒ p – q = 1 ...(i) and p(–1)3 + (–1)2 – 2(–1) – q = 0 ⇒ p + q = 3 ...(ii) Solving (i) and (ii) p = 2, q = 1. |
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802. |
Write the degree of the polynomial for each of the following. i. 5 + 3x4 ii. 7 iii. ax7 + bx9 (a, b are constants) |
Answer» i. 5 + 3x4 Here, the highest power of x is 4. ∴Degree of the polynomial = 4 ii. 7 = 7x° ∴ Degree of the polynomial = 0 iii. ax7+ bx9 Here, the highest power of x is 9. ∴Degree of the polynomial = 9 |
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803. |
(2x – 3y)3 + (3y – 4z)3 + (4z – 2x)3 can be factorised into which one of the following ?(a) (2x + 3y + 4z) (2x – 3y – 4z) (b) (2x + 3y – 4z) (2x – 3y + 4z) (c) (2x – 3y) (3y – 4z) (4z – 2x) (d) 6 (2x – 3y) (3y – 4z) (2z – x) |
Answer» (d) 6.(2x – 3y)(3y – 4z)(2z – x). Since (2x – 3y) + (3y – 4z) + (4z – 2x) = 0, therefore, (2x – 3y)3 + (3y – 4z)3 + (4z – 2x)3 (Take out 2 common) = 3.(2x – 3y)(3y – 4z) (4z – 2x) = 6.(2x – 3y)(3y – 4z)(2z – x). |
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804. |
For what value of k, will the expression (3x3 – kx2 + 4x + 16) be divisible by (x –\(\frac{k}{2}\)) ?(a) 4 (b) –4 (c) 2 (d) 0 |
Answer» (b) – 4. Let f(x) = 3x3 – kx2 + 4x + 16. Then, f(x) will be divisible by \(\big(\)x – \(\frac{k}{2}\)\(\big)\) if f\(\big(\frac{k}{2}\big)\) = 0 ⇒ 3.\(\big(\frac{k}{2}\big)\)3 – k.\(\big(\frac{k}{2}\big)\)2 + 4\(\big(\frac{k}{2}\big)\) + 16 = 0 ⇒ \(\frac{3k^3}{8}\) - \(\frac{k^3}{4}\) + \(\frac{4k}{2}\) + 16 = 0 ⇒ \(\frac{3k^3-2k^3+16k+128}{8}\) = 0 ⇒ k3 + 16k + 128 = 0 ⇒ (k + 4) (k2 – 4k + 32) = 0 ⇒ k + 4 = 0 ⇒ k = – 4. |
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805. |
If p (x) = x2 – 4x + 3, then evaluate p(2) – p (-1) + p ( ½). |
Answer» Given that, p() =x2 – 4x + 3 According to the question, When x = 2, p(x) = p(2) p() =x2 – 4x + 3 Substituting x = 2, p(2) = (2)2 – 4(2) + 3 = 4 – 8 + 3 = – 4 + 3 = – 1 When x = – 1, p(x) = p(– 1) p() =x2 – 4x + 3 Substituting x = – 1, p(– 1) = (– 1)2 – 4(– 1) + 3 = 1 + 4 + 3 = 8 When x = ½ , p(x) = p(½) p() =x2 – 4x + 3 Substituting x = ½, p(½) = (½)2 – 4(½) + 3 = ¼ – 2 + 3 = ¼ + 1 = 5/4 Now, p(2)− p(−1) + p(½) = – 1 – 8 + (5/4) = – 9 + (5/4) = ( – 36 + 5)/4 = – 31/4 |
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806. |
If p(x) = x3 + 2x2 – 3x + 1 and q(x) = x3 – 2x2 + 3x + 5(a) Find p(x) + q(x). What is its degree?(b) Find p(x) – q(x). What is its degree? |
Answer» (a) p(x) = x3 + 2x2 – 3x + 1, q(x) = x3 – 2x2 + 3x + 5 p(x) + q(x) = x3 + 2x2 – 3x + 1 + x3 – 2x2 + 3x + 5 = 2x3 + 6 Degree = 3 (b) p(x) – q(x) = x3 + 2x2 – 3x + 1 – (x3 – 2x2 + 3x + 5) = x3 + 2x2 – 3x + 1 -x3 + 2x2 – 3x – 5 = 4x2 – 6x – 4 Degree = 2 |
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807. |
If x3 + px + q and x3 + qx + p have a common factor, then which of the following is correct ?(a) p + q = 0 (b) p + q – 1 = 0 (c) (p + q + 1) = 0 (d) p – q + 1 = 0 |
Answer» (c) (p + q + 1) = 0. Let the common factor be x – α, then x = α will make the given expressions zero, i.e., α2 + pα + q = 0 α2 + qα + p = 0 Solving by the rule of cross-multiplication, we have \(\frac{α^2}{p^2-q^2}\) = \(\frac{α}{q-p}\) = \(\frac{1}{q-p}\) From, last two relation, α = 1. ⇒ α2 = \(\frac{p^2-q^2}{q-p}\) ⇒ 1 = – (p + q) ⇒ p + q + 1 = 0. |
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808. |
Find the value of k, if `x-1`is a factor of p(x) in each of the following cases:(i) `p(x)=x^2+x+k` (ii) `p(x)=2x^2+k x+sqrt(2)`(iii) `p(x)=k x^2-sqrt(2)x+1`(iv) `p(x)=k x^2-3x+k` |
Answer» Here, `(x-1)` is a factor of ` p(x)` that means from Factor theorem, `p(1) = 0.` `(i) p(x) = x^2+x+k` As, `p(1)` is `0` `0 = 1^2+1+k=>k=-2` `(ii) p(x) = 2x^2+kx+sqrt2` As, `p(1)` is `0` `2+k+sqrt2 = 0=>k = -(2+sqrt(2))` `(iii) p(x) = kx^2-sqrt2x+1` As, `p(1)` is `0` `k-sqrt2+1 = 0=>k = sqrt2-1` `(iv) p(x) = kx^2-3x+k` As, `p(1)` is `0` `k-3+k=0 =>2k = 3` `k=3/2` |
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809. |
Find the value of the polynomial 3x3 – 4x2 + 7x – 5, when x = 3 and also when x = -3. |
Answer» Given that, p(x) = 3x3 – 4x2 + 7x – 5 According to the question, When x = 3, p(x) = p(3) p(x) = 3x3 – 4x2 + 7x – 5 Substituting x = 3, p(3)= 3(3)3 – 4(3)2 + 7(3) – 5 p(3) = 3(3)3 – 4(3)2 + 7(3) – 5 = 3(27) – 4(9) + 21 – 5 = 81 – 36 + 21 – 5 = 102 – 41 = 61 When x = – 3, p(x) = p(– 3) p(x) = 3x3 – 4x2 + 7x – 5 Substituting x = – 3, p(– 3)= 3(– 3)3 – 4(– 3)2 + 7(– 3) – 5 p(– 3) = 3(–3)3 – 4(–3)2 + 7(–3) – 5 = 3(–27) – 4(9) – 21 – 5 = –81 – 36 – 21 – 5 = –143 |
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810. |
In the polynomial p(x) = 3x2 – ax + 1,Find ‘a’ satisfying p(1) = 2. |
Answer» p(x) = 3x2 – ax + 1 p(1) = 3(1)2 – (a × 1) + 1 = 3 – a + 1 = 4 – a Given p(1) = 2 That is, 4 – a = 2 , a = 4 – 2 = 2 |
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811. |
The sum of \((\frac{x-1}{x+1})\) and its reciprocal is ………………A) \(\frac{x^2+1}{x^2-1}\)B) \(\frac{2(x^2+1)}{x^2-1}\)C) \(\frac{x^2-1}{x^2+1}\)D) \(\frac{2(x^2-1)}{x^2+1}\) |
Answer» Correct option is (B) \(\frac{2(x^2+1)}{x^2-1}\) Sum of \(\left(\frac{x-1}{x+1}\right)\) and its reciprocal \(=\frac{x-1}{x+1}+\frac{x+1}{x-1}\) \(=\frac{(x-1)^2+(x+1)^2}{(x+1)(x-1)}\) \(=\frac{(x^2-2x+1)+(x^2+2x+1)}{x^2-1}\) \(=\frac{2(x^2+1)}{x^2-1}\) Correct option is B) \(\frac{2(x^2+1)}{x^2-1}\) |
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812. |
What is/are the factors of (x29 – x24 + x13 – 1) ?(a) (x – 1) only (b) (x + 1) only (c) (x – 1) and (x + 1) (d) Neither (x – 1) nor (x + 1) |
Answer» (a) (x – 1) only For (x – 1) to be a factor of the given expression, the value of expression at x = 1 is (1)29 – (1)24 + (1)13 – 1 = 1 – 1 + 1 – 1 = 0 ∴ (x – 1) is a factor of x29 – x24 + x13 – 1 Similarly for (x + 1) to be the factor, the value of expression at x = – 1 is (–1)29 – (–1)24 + (–1)13 – 1 = – 1 – 1 – 1 – 1 = – 4 ≠ 0 ∴ (x + 1) is not a factor of x29 – x24 + x13 – 1. Hence, (a) is the correct option. |
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813. |
7x3 – 4x2 – x + 4 is a polynomial.a. Write the terms of the polynomial.b. Write the coefficient of x2.c. Write the constant terms of the polynomial.d. What is the degree of the polynomial ? |
Answer» a. Terms = 7x2, -4x2, -x, 4 b. Coefficient of x2 = -4 c. Constant term = 4 d. Degree of the polynomial = 3 |
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814. |
The value of 6a + 11b if x3 – 6x2 + ax + b is exactly divisible by (x2 – 3x + 2) is ………………A) 0 B) 66 C) 132 D) 1 |
Answer» Correct option is (A) 0 \(\because\) (x - 1) & (x - 2) are factors of \((x^3 – 6x^2 + ax + b)\) \((\because\) (x - 1) (x - 2) \(=x^2-3x+2)\) \(\therefore\) x = 1 and x = 2 are zeros of \((x^3 – 6x^2 + ax + b)\) \(\therefore\) 1-6+a+b = 0 and 8-24+2a+b = 0 \(\Rightarrow\) a+b = 5 and 2a+b = 16 \(\Rightarrow\) (2a+b) - (a+b) = 16 - 5 \(\Rightarrow\) a = 11 \(\therefore\) b = 5 - a = 5 - 11 = -6 \(\therefore\) 6a+11b \(=6\times11+11\times-6\) = 66 - 66 = 0 Correct option is A) 0 |
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815. |
Find “a” and “b” in order that x3 – 6x2 + ax + b may be exactly divisible by x2 – 3x + 2. A) a = 11, b = -5 B) a = 11, b = 6 C) a = 11, b = -6 D) a = -11, b = -5 |
Answer» Correct option is (C) a = 11, b = -6 \((x^2 – 3x + 2)\) is a factor of \((x^3-6x^2+ax+b)\) \(\Rightarrow\) (x-1) & (x-2) are factors of \((x^3-6x^2+ax+b)\) \((\because\) (x-1) (x-2) \(=x^2 – 3x + 2)\) \(\Rightarrow\) x = 1 & x = 2 are zeros of \((x^3-6x^2+ax+b)\) \(\therefore\) 1 - 6 + a + b = 0 and 8 - 24 + 2a + b = 0 \(\Rightarrow\) a+b = 5 and 2a+b = 16 \(\Rightarrow\) (2a+b) - (a+b) = 16 - 5 \(\Rightarrow\) a = 11 \(\therefore\) b = 5 - a = 5 - 11 = -6 Correct option is B) a = 11, b = 6 |
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816. |
If the expressions (px3 + 3x2 – 3) and (2x3 – 5x + p) when divided by (x – 4) leave the same remainder, then what is the value of p ? |
Answer» Let f(x) = px3 + 3x2 – 3 g(x) = 2x3 – 5x + p When divisible by x – 4, the remainders for the given expressions are f(4) and g(4) respectively. f(4) = p(4)3 + 3(4)2 – 3 = 64p + 48 – 3 = 64p + 45 g(4) = 2(4)3 – 5(4) + p = 128 – 20 + p = 108 + p. Given, f(4) = g(4) ⇒ 64p + 45 = 108 + p ⇒ 63 p = 63 ⇒ p = 1. |
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817. |
Simplify the followingi. (2x + 1) (3x + 4) (4x + 3) (3x + 4)ii. (3x + 4)2 – (2x – 1) (3x + 4) |
Answer» i. (2x + 1) (3x + 4) (4x + 3) (3x + 4) = (3x + 4) [(2x + 1 + 4x + 3)] = (3x + 4) [6x + 4] = (3x x (6x) + (3x) x (4)+ 4x(6x) + 4 x 4 = 18x2 + 12x + 24x + 16 = 18x2 + 36x + 16 ii. (3x + 4)2 – (2x – 1) (3x + 4) = (3x + 4) [3x + 4 – (2x – 1)] = (3x + 4)[3x + 4 – 2x + 1] = (3x + 4) (x + 5) = 3x2 + 15x + 4x + 20 = 3x2 + 19x + 20 |
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818. |
If x5 – 9x2 + 12x – 14 is divisible by (x – 3), what is the remainder ? |
Answer» Let f(x) = x5 – 9x2 + 12x – 14 f(x) is divisible by (x – 3) so remainder = f(3). ∴ f(3) = (3)5 – 9(3)2 + 12(3) – 14 = 243 – 81 + 36 – 14 = 184. |
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819. |
In a polynomial p(x) = 2x3 – 7x2 + kx + 20,p(2) = p(3).a. Find the value of k. b. Using the value of k, write the polynomial. c. Find p(1). |
Answer» a. p(2) = 2 × 22 – 7 × 22 + k × 2 + 20 = 16 – 28 + 2k + 20 = 8 + 2k p(3) = 2 × 33 – 7 × 32 + k × 3 + 20 = 54 – 63 + 3k + 20 = 11 + 3k P(2) = P(3) 8 + 2k = 11 + 3k k = -3 b. p(x) = 2x3 – 7x2 - 3x + 20 c. p(1) = 2 – 7 – 3 + 20 = 12 |
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820. |
Find the remainder when `x^(3)-ax^(2)+6x-a` is divided by x-a. |
Answer» The zero of x-a is a. Let `p(x)=x^(3)-ax^(2)+6x-a` So, `p(a)=a^(3)-a(a)^(2)+6a-a=a^(3)-a^(3)+5a` `implies p(a)=5a` `therefore` Required remainder =5a |
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821. |
Find the remainder when x4 + 15x3 + 6x2 – 12x + 3 is divided by x + 2 ? ……………A) -101B) 53 C) -52 D) 52 |
Answer» Correct option is (A) -101 Let \(p(x)=x^4+15x^3+6x^2+12x+3\) Remainder when p(x) is divided by x+2 is \(p(-2)=(-2)^4+15(-2)^3\) \(+6(-2)^2+12(-2)+3\) = 16 - 120 + 24 - 24 + 3 = -101 Correct option is A) -101 |
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822. |
In a polynomial p(x) = 2x3 + 9x2 + kx + 3, p(-2) = p(-3). Find the value of k. |
Answer» p(x) = 2x3 + 9x2 + kx + 3 p(-2) = 2(-2)3 + 9(-2)2 + k(-2) + 3 = -16 + 36 – 2k + 3 = 23 – 2k p(-3) = 2(-3)3 + 9(-3)2 + k(-3) + 3 = -54 + 81 – 3k + 3 = 30 – 3k We have p(-2) = p(-3), 23 -2k = 30 -3k -2k + 3k = 30 – 23 k = 7 |
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823. |
In a polynomial p(x) = 2x3 + ax2 – 7x + b. p(1) = 3, p(2) = 19. Then find the value of ‘a’ and ‘b’? |
Answer» p(x) = 2x3 + ax2 – 7x + b We have p(1) = 3. p(1) = 2 x 13 + a x 12 – 7 x 1 + b = 3 2 + a – 7 + b = 3 a + b – 5 = 3 a + b = 8 ………. (1) We have p(2) = 19. p(2 ) = 2 x 23 + a x 22 – 7 x 2 + b = 19 16 + 4a – 14 + b = 19 4a + b + 2 = 19 4a + b = 17…….. (2) From equation (1), (2) (2) – (1) 4a + b = 17 \(\frac{a+b=8}{3a=9}\) a = 9/3 = 3 From equation (1) a + b = 8 3 + b = 8 b = 5 |
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824. |
Use the Factor Theorem to determine whether g(x) is a factor of p(x) in each of the following cases : (i) p(x) = 2x3 + x2 – 2x – 1, g(x) = x+1 (ii) p(x) = x3 + 3x2 + 3x + 1, g(x) = x + 2 (iii) p(x) = x3 – 4x2 + x + 6, g(x) = x – 3 |
Answer» (i) p(x) = 2x3 + x2 – 2x – 1 g(x) = x + 1 If x + 1 = 0, then x = -1 p(x) = 2x3 + x2 – 2x – 1 p(-1)= 2(-1)3 + (-1)2 -2(- 1) – 1 = 2(-1) + (1) + 2 – 1 = -2 + 1 + 2 – 1 P(-1)= 0 Here, r(x) = p(a) = 0, ∴ g(x) is the a factor f(x) (ii) p(x) = x3 + 3x2 + 3x + 1 g(x) = x + 2 If x + 2 = 0, then x = -2 ∴ p(x) = x3 + 3x2 + 3x + 1 p(-2) = (-2)3 + 3(-2)2 + 3 (-2) + 1 = -8 + 3(4) + 3(-2) + 1 = -8 + 12 – 6 + 1 = 13 – 24 p(-2)= -11 Here we have r(x) = p(a) =-11. Value of r(x) is not equal to zero. ∴ g(x) is not a factor of f(x). (iii) p(x) = x3 – 4x2 + x + 6 g(x) = x – 3 Let, x – 3 = 0, then x = 3 p(x) = x3 – 4x2 + x + 6 p(3) = (3)2 – 4(3)2 + 3 + 6 = 27 – 4(9) + 3 + 6 = 27 – 36 + 3 + 6 = 36 – 36 p(3) = 0 Here, we have r(x) = p(a) = 0 ∴ (x – 3) is the factor of p(x). |
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825. |
Determine which of the following polynomials has (x+1) a factor : (i) x3 + x2 + x + 1 (ii) x4 + x3 + x2 + x + 1 (iii) x4 + 3x3 + 3x2 + x + 1 (iv) x3 – x2 – (2 + √2)x + √2 |
Answer» (i) x- 1 is a factor of p(x) x + 1 = x – a a = -1 For the value of p(a), value of r(x) = 0. ∴ p(x) = x3 + x2 + x + 1 p(-1)= (-1)3 + (-1)2 + (-1) + 1 = -1 + 1 -1 + 1 p(-1)= 0 Here, p(a) = r(x) = 0 ∴ x + 1 is a factor. (ii) If x + 1 = x – a, then a = -1 p(x) = x4 + x3 + x2 + x + 1 p(-1)= (-1)4 + (-1)3 +(-1)2 + (-1)+ 1 = 1 – 1 + 1 – 1 + 1 = 3 – 2 p(-1)= 1 Here, r(x) = p(a)= 1 Reminder is not zero. ∴ x+1 is not a factor. (iii) If x + 1 = x – a then a = -1 p(x) = x4 + 3x3 + 3x2 + x + 1 p(-1) = (-1)4 + 3(-1 )3 +3(-1 )2 + (-1) + 1 = 1 + 3(-1) + 3(1) + 1(-1) + 1 = 1- 3 + 3 – 1 + 1 = 5 – 4 P(-1)= 1 Here, r(x) = p(a) = 1 Remainder is not zero ∴ x+1 is not a factor. (iv) If x + 1 = x – a then, a = -1 p(x) = x3 – x2 – (2 + √2)x+ p(-1) = (-1)3 – (-1)2 -(2 + √2)(-1) + √2 = -1 -(+1) – (2 – √2) + √2 = -1 – 1 + 2 + √2 +√2 = -2 + 2 + √2 = + 2√2 p(-1) = 2√2 Here, r(x) = p(a) = 2√2 Value of remainder r(x) is not zero. ∴ x + 1 is not a factor. |
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826. |
Find p(0), p(1) and p(-1) in the following polynomials,i. p(x) = 3x + 5ii. p(x) = 3x2 + 6x + 1iii. p(x) = 2x2 – 3x + 4iv. p(x) = 4x3 + 2×2 + 3x + 7v. p(x) = 5x3 – x2 + 2x – 3 |
Answer» i. p(x) = 3x + 5 p(0) = 3 × 0 + 5 = 5 p(1) = 3 × 1 + 5 = 8 p(-1) = 3 x - 1 + 5 = 2 ii. p(x) = 3x2 + 6x + 1 p(0) = 3 × 02 + 6 × 0 + 1 = 1 p(1) = 3 × 12 + 6 × 1 + 1 = 10 p(-1) = 3 × (-1)2 + 6 × (-1) + 1 = -2 iii. p(x) = 2x2 – 3x + 4 p(0) = 2 × 02 – 3 × 0 + 4 = 4 p(1) = 2 × 12 – 3 × 1 + 4 = 3 p(-1) =2 × (-1)2 – 3 × (-1) + 4 = 9 iv. p(x) = 4x3 + 2x2 + 3x + 7 p(0) = 4 × 03 + 2 × 02 + 3 × 0 +7 = 7 p(1) = 4 × 13 + 2 × 12 + 3 × 1 + 7 = 16 p(-1) = 4 × (-1)3 + 2 × (-1)2 + 3 × (-1) +7 = 2 v. p(x) = 5x3 – x2 + 2x – 3 p(0) = 5 × 03 – 02 + 2 × 0 – 3 =-3 p(1) = 5 × 13 – 12 + 2 × 1 – 3 = 3 p(-1) = 5 × (-1)3 – (-1)2 + 2 × (-1) – 3 = -11 |
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827. |
Find p(1) and p(10) in the following polynomials,i. p(x) = 2x + 5 ii. p(x) = 3x2 + 6x + 1 iii. p(x) = 4x3 + 2x2 + 3x + 7 |
Answer» i. p(x) = 2x + 5 p(1) = 2 × 1 + 5 = 2 + 5 = 7 p(10) = 2 × 10 + 5 = 20 + 5 = 25 ii. p(x) = 3x2 + 6x + 1 p(1) = 3 × 12 + 6 x 1 + 1 = 3 + 6 + 1 = 10 p(10) = 3 × 102 + 6 × 10 + 1 = 300 + 60 + 1 = 361 iii. p(x) = 4x3 + 2x2 + 3x + 7 p(1) = 4 × 13 + 2 × 12 + 3 × 1 + 7 = 4 + 2 + 3 + 7 = 16 p(10) = 4 × 103 + 2 × 102 + 3 × 10 + 7 = 4000 + 200 + 30 + 7 = 4237 |
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828. |
Factorize the polynomials. (x2 – 6x)2 – 8(x2 – 6x + 8) – 64 |
Answer» (x2 – 6x)2 – 8(x2 – 6x + 8) – 64 = m2 – 8(m + 8)-64 …[Putting x2 – 6x = m] = m2 – 8m – 64 – 64 = m2 – 8m – 128 = m2 – 16m + 8m- 128 = m(m – 16) + 8(m – 16) = (m – 16)(m + 8) = (x2 – 6x – 16) (x2 – 6x + 8) … [Replacing m = x2 – 6x] = (x2 – 8x + 2x – 16) (x2 – 4x – 2x + 8) = [x(x – 8) + 2(x – 8)] [x(x – 4) – 2(x – 4)] = (x – 8) (x + 2) (x – 4) (x – 2) |
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829. |
Evaluate the products without actual multiplication :101 x 99 |
Answer» 101 x 99 = (100 + 1) (100 – 1) = 1002 – 12 = 10000 – 1 = 9999 |
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830. |
Factorize the polynomials.(y + 2) (y – 3) (y + 8) (y + 3) + 56 |
Answer» (y + 2) (y – 3) (y + 8) (y + 3) + 56 = (y + 2)(y + 3)(y – 3)(y + 8) + 56 = (y2 + 3y + 2y + 6) (y2 + 8y – 3y – 24) + 56 = (y2 + 5y + 6) (y2 + 5y – 24) + 56 = (m + 6) (m – 24) + 56 … [Putting y2 + 5y = m] = m (m – 24) + 6 (m – 24) + 56 = m2 – 24m + 6m – 144 + 56 = m2 – 18m – 88 = m2 – 22m + 4m – 88 = m(m – 22) + 4(m – 22) = (m – 22) (m + 4) = (y2 + 5y – 22)(y2 + 5y + 4) … [Replacing m = y2 + 5y] = (y2 + 5y – 22) (y2 + 4y + y + 4) = (y2 + 5y – 22) [y(y + 4) + 1(y + 4)] = (y2 + 5y – 22) (y + 4) (y + 1) |
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831. |
Number of zeroes of x2 – 7x + 12 is ……………A) 4 B) 7 C) 2 D) 1 |
Answer» Correct option is (C) 2 \(x^2 – 7x + 12=0\) \(\Rightarrow\) (x - 3) (x - 4) = 0 \(\Rightarrow\) x = 3 or x = 4 \(\therefore\) Number of zeros of \(x^2 – 7x + 12\) is 2. Correct option is C) 2 |
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832. |
Divide p(x) by g(x) in each of the following questions and find the quotient q(x) and remainder r(x) : `p(x)=x^(4)+6x^(3)-4x^(2)+2x+1, " " g(x)=x^(2)+3x-1` |
Answer» Correct Answer - `q(x)=x^(2)+3x-12, " "r(x)=41x-11` |
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833. |
The product of two consecutive numbers is 56. Find ……………A) -8, -7B) 8, -7C) -8, 7D) 8, 7 |
Answer» Correct option is (A) -8, -7 Let consecutive numbers are x & (x+1). \(\therefore\) x (x+1) = 56 \(\Rightarrow\) \(x^2+x-56=0\) \(\Rightarrow\) \(x^2+8x-7x-56=0\) \(\Rightarrow\) x (x+8) - 7 (x+8) = 0 \(\Rightarrow\) (x-7) (x+8) = 0 \(\Rightarrow\) x = 7 or x = -8 \(\therefore\) Consecutive numbers either -8, -7 or 7, 8. Correct option is A) -8, -7 |
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834. |
Expand : (i) `(4a-5b)^(3) " " (ii) (a+2b)^(3)` |
Answer» `(i) (4a-5b)^(3)=(4a)^(3)-(5b)^(3)-3xx4axx5b(4a-5b)` `=64a^(3)-125b^(3)-60ab(4a-5b)=64a^(3)-125b^(3)-240a^(2)b+300ab^(2)` `(ii) (a+2b)^(3)=(a)^(3)+(2b)^(3)+3xxaxx2b(a+2b)` `=a^(3)+8b^(3)+6ab(a+2b)=a^(3)+8b^(3)+6a^(2)b+12ab^(2)` |
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835. |
If we divide 36x2 – 12x + 1- 49y2 by 6x + 7y -1, then the quotient is ……………… A) 6x + 1 + 7y B) 6x – 1 – 7y C) 6x + 2 + 7y D) -6x -1 – 7y |
Answer» Correct option is B) 6x – 1 – 7y |
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836. |
Find the product using appropriate identities (i) (x+5)(x+5) (ii) (x+4)(x-4) (iii) (x+5)(x+3) (iv) (x-5)(x+3) |
Answer» (i) We know that `(x+y)^(2)=x^(2)+2xy+y^(2)` Now, `(x+5)(x+5)=(x+5)^(2)=x^(2)+2xx x xx5+5^(2)=x^(2)+10x+25` (ii) We know that `(x+a)(x-a)=x^(2)-a^(2)` Now, `(x+4)(x-4)=x^(2)-4^(2)=x^(2)-16` (iii) We know that `(x+a)(x+b)=x^(2)+(a+b)x+ab` Now, `(x+5)(x+3)=x^(2)+(5+3)x+5xx3=x^(2)+8x+15` (iv) We know that `(x-a)(x+b)=x^(2)+(-a+b)x+(-a)xxb` Now, `(x-5)(x+3)=x^(2)+(-5+3)x+(-5)xx3=x^(2)-2x-15` |
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837. |
Factorise : `(i) 36x^(2)+60xy+25y^(2) (ii) (49)/(9)x^(2)-(35)/(6)xy+(25)/(16)y^(2)` |
Answer» `(i) 36x^(2)+60xy+25y^(2)` We can write it `(6x)^(2)+2xx6xx5y+(5y)^(2)=(6x+5y)^(2)` `=(6x+5y)(6x+5y)` (ii) `(49)/(9)x^(2)-(35)/(6)xy+(25)/(16)y^(2)` We can write it `((7)/(3)x)^(2)-2xx(7)/(3)x xx(5)/(4)y+((5)/(4)y)^(2)` `=((7)/(3)x-(5)/(4)y)^(2)=((7)/(3)x-(5)/(4)y)((7)/(3)x-(5)/(4)y)` |
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838. |
If A = \(\frac{2x+1}{2x-1}\) and B = \(\frac{2x-1}{2x+1},\) then A - B is equal to :(a) \(\frac{1}{4x^2-1}\)(b) \(\frac{8}{4x^2-1}\)(c) \(\frac{-2}{4x^2-1}\)(d) \(\frac{4x}{4x^2-1}\) |
Answer» (b) \(\frac{8}{4x^2-1}\) A - B = \(\frac{2x+1}{2x-1}\) - \(\frac{2x-1}{2x+1}\) = \(\frac{(2x+1)^2 -(2x-1)^2}{(2x-1)(2x+1)}\) = \(\frac{(4x^2+4x+1)-(4x^2-4x+1)}{4x^2-1}\) = \(\frac{8}{4x^2-1}\) |
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839. |
\(\frac{1}{x+1}-\frac{1}{x-1}-\frac{x^2}{x+1}+\frac{x^2}{x-1},\) when simplified is equal to :(a) 0 (b) 1 (c) 2 (d) –2 |
Answer» (c) 2 \(\frac{1}{x+1}-\frac{1}{x-1}-\frac{x^2}{x+1}+\frac{x^2}{x-1}\) = \(\frac{(x-1)-(x+1)-x^2(x-1)+x^2(x+1)}{(x-1)(x+1)}\) = \(\frac{x-1-x-1-x^3+x^2+x^3+x^2}{x^2-1}\) = \(\frac{2x^2-2}{x^2-1}=\frac{2(x^2-1)}{(x^2-1)}\) = 2 |
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840. |
\(\bigg(\frac{2x+y}{x+y}-1\bigg)÷\bigg(1-\frac{y}{x+y}\bigg)\) id equal to :(a) x (b) y (c) xy (d) 1 |
Answer» (d) 1 \(\bigg(\frac{2x+y}{x+y}-1\bigg)÷\bigg(1-\frac{y}{x+y}\bigg)\) = \(\bigg[\frac{2x+y-(x+y)}{x+y}\bigg]÷\bigg[\frac{x+y-y}{x+y}\bigg]\) = \(\frac{x}{x+y}\times\frac{x+y}{x}=1\) |
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841. |
The HCF of two polynomials \(4x^2(x^2 - 3x + 2)\) and \(12x(x - 2)(x^2 - 4)\) is 4x(x - 2). The LCM of the two polynomials is : (a) 12x (x2 - 4)(b) 12x2 (x2 - 3x + 4)(x2 - 2)(c) 12x2 (x2 - 3x + 2)(x2 - 4)(d) 12x(x2 - 3x - 2)(x2 - 4) |
Answer» (c) 12x2(x2 - 3x +2)(x2 - 4) LCM = \(\frac{\text{product of the polynomials}}{HCF}\) = \(\frac{4x^2(x^2-3x+2)\times12x(x-2)(x^2-4)}{4x(x-2)}\) = \(\frac{4x^2(x-2)(x-1)\times12x(x-2)(x-2)(x+2)}{4x(x-2)}\) = 12x2(x - 1)(x - 2)(x - 2)(x + 2) = 12x2(x2 - 3x +2)(x2 - 4) |
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842. |
The LCM of the polynomials \(x^3 + 3x^2 +3x +1\), \(x^2 + 2x + 1\) and \(x^2 - 1\) is:(a) (x2 - 1)(x + 1)3(b) (x2 + 1)(x - 1)2(c) (x2 - 1)(x - 1)2(d) (x + 1)3 |
Answer» (a) (x2 - 1)(x + 1)3 \(x^3 + 3x^2 +3x +1\) = (x + 1)3 \(x^2 + 2x + 1\) = (x + 1)2 \(x^2 - 1\) = (x + 1)(x - 1) ∴ Reqd. LCM = (x - 1)(x + 1)3 = (x2 - 1)(x + 1)3 |
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843. |
The product of the rational expressions \(\frac{x^2 - y^2}{x^2+2xy+y^2}\) and \(\frac{xy+y^2}{x^2 - xy}\) is :(a) xy (b) y/x (c) x/y (d) 1 |
Answer» (b) \(\frac{y}{x}\) Reqd. product = \(\frac{x^2 - y^2}{x^2+2xy+y^2}\) x \(\frac{xy+y^2}{x^2 - xy}\) = \(\frac{(x + y)(x + y)}{(x+y)^2}\times\frac{y(x+y)}{x(x-y)}\) = \(\frac{y}{x}\) |
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844. |
If x + y + z = 0, show that x3 + y3 + z3 = 3xyz. |
Answer» x + y + z = 0 x + y = -z by cubing on both sides, (x + y)3 = (-z)3 x3+ y3 + 3xy(x + y) = -z3 x3 + y3 + 3xy (-z) = -z (∵ x + y =-z data given) x3 + y3 – 3xyz = -z3 ∴ x3 + y3 + z3 = 3xyz. |
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845. |
\(\frac{x^3+y^3+z^3-3xyz}{a^3+b^3+c^3-3abc}\times\frac{a^2+b^2+c^2-ab-bc-ca}{x^2+y^2+z^2-xy-yz-zx}\) equlas(a) 1 (b) \(\frac{x^2+y^2+z^2}{a^2+b^2+c^2}\)(c) \(\frac{x+y+z}{a+b+c}\)(d) \(\frac{xyz}{abc}\) |
Answer» (c) \(\frac{x+y+z}{a+b+c}\) Reqd. exp. = \(\frac{(x+y+z)(x^2+y^2+z^2-xy-yz-zx)}{(a+b+c)(a^2+b^2+c^2-ab-bc-ca)}\times\frac{a^2+b^2+c^2-ab-bc-ca}{x^2+y^2+z^2-xy-yz-zx}\) = \(\frac{x+y+z}{a+b+c}\) |
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846. |
Verify that x3 + y3 + z3 – 3xyz = 1/2 (x + y + z) [(x – y)2 + (y – z)2 + (z – x)2 ] (OR) Verify that p3 + q3 + r3 – 3pqr = 1/2 (p + q + r) [(p – q)2 + (q – r)2 + (r – p)2 ] |
Answer» Given x3 + y3 + z3 – 3xyz = 1/2 (x + y + z) [(x – y)2 + (y – z)2 + (z – x)2] R-H.S = 1/2 (x + y + z) [(x – y)2 + (y – z)2 + (z – x)2 ] = 1/2 (x + y + z) [x2 + y2 – 2xy + y2 + z2 – 2yz + z2 + x2 – 2xz] = 1/2 (x + y + z) [2x2 + 2y2 + 2z2 – 2xy – 2yz – 2zx] = 1/2 (x + y + z) (2) [x2 + y2 + z2 – xy – yz – zx] = (x + y + z) (x2 + y2 + z2 – xy – yz – zx) = L.H.S Hence proved. |
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847. |
If x + y + z = 0, show that x3 + y3 + z3 = 3xyz |
Answer» Given x + y + z = 0 To prove x3 + y3 + z3 = 3xyz We have an identity (x + y + z) (x2 + y2 + z2 – xy – yz – zx) = x3 + y3 + z3 – 3xyz Substituting x + y + z = 0in the above equation, we get 0 x (x2 + y2 + z2 -xy-yz-zx) = x3 + y3 + z3 – 3xyz ⇒ x3 + y3 + z3 – 3xyz = 0 ⇒ x3 + y3 + z3 = 3xyz |
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848. |
Verify that `x^(3)+y^(3)+z^(3)-3xyz=(1)/(2)(x+y+z)[(x-y)^(2)+(y-z)^(2)+(z-x)^(2)]` |
Answer» `R.H.S. = 1/2(x+y+z)[(x-y)^2+(y-z)^2+(z-x)^2]` `=1/2(x+y+z)(x^2+y^2-2xy+y^2+z^2-2yz+z^2+x^2-2zx)` `=1/2(x+y+z)(2x^2+2y^2+2z^2-2xy-2yz-2zx)` `=(x+y+z)(x^2+y^2+z^2-xy-yz-zx)` We have the formula, `x^3+y^3+z^3 -3xyz =(x+y+z)(x^2+y^2+z^2-xy-yz-zx)` Thus, `L.H.S. = R.H.S.` |
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849. |
Find the zeros of the quadratic polynomials 8x2 - 4 and verify the relationship between the zeros and the coefficients. |
Answer» Let f(x) = 8x2 – 4 = 4 ((√2x)2 – (1)2) = 4(√2x + 1)(√2x – 1) To find the zeroes, set f(x) = 0 (√2x + 1)(√2x – 1) = 0 (√2x + 1) = 0 or (√2x – 1) = 0 x = (-1)/√2 or x = 1/√2 So, the zeroes of f(x) are (-1)/√2 and x = 1/√2 Again, Sum of zeroes = -1/√2 + 1/√2 = (-1+1)/√2 = 0 = -b/a = (-Coefficient of x)/(Cofficient of x2) Product of zeroes = -1/√2 x 1/√2 = -1/2 = -4/8 = c/a = Constant term / Coefficient of x2 |
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850. |
Simplify \(\frac{1}{1+x+x^2}\) - \(\frac{1}{1-x+x^2}\) + \(\frac{2x}{1+x^2+x^4}\).............A) \(\frac{1}{1+x^2+x^4}\)B) 0 C) \(\frac{-1}{1+x^2+x^4}\)D) \(\frac{2x-3}{1+x^2+x^4}\) |
Answer» Correct option is (B) 0 \(\frac{1}{1+x+x^2}-\frac{1}{1-x+x^2}+\frac{2x}{1+x^2+x^4}\) \(=\frac{(1-x+x^2)-(1+x+x^2)}{(1+x^2+x)(1+x^2-x)}+\frac{2x}{1+x^2+x^4}\) \(=\frac{-2x}{(1+x^2)^2-x^2}+\frac{2x}{1+x^2+x^4}\) \(=\frac{-2x}{1+x^4+2x^2-x^2}+\frac{2x}{1+x^2+x^4}\) \(=\frac{-2x}{1+x^2+x^4}+\frac{2x}{1+x^2+x^4}=0\) Correct option is B) 0 |
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