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551.

यदि `x-1/x=3` है तो `x^(3)-1/(x^(3))` का मान क्या होगा?A. 32B. 36C. 40D. 49

Answer» Correct Answer - B
`x-1/x=3`
`x^(3)-1/(x^(3))-3(x-1/x)=27`
`x^(3)-1/(x^(3))=27+3xx3`
`=27+9=36`
552.

यदि `x+y=7` है तो `x^(3)+y^(3)+21xy` का मान क्या होगा?A. 243B. 143C. 343D. 443

Answer» Correct Answer - C
`x+y=7` (cubing both sides)
`(x+y)^(3)=(7)^(3)`
`x^(3)+y^(3)=3(x+y)xy=343`
`x^(3)+y^(3)+21xy=343`
` x^(3)+y^(3)+21xy=343`
553.

यदि `x+1/x=3` है तो `(x^(5)+1)/(x^(5))` का मान ज्ञात करें।A. 322B. 126C. 123D. 113

Answer» Correct Answer - C
`x+1/x=3`
(Squaring both sides)
`x^(2)+1/(x^(2))=7`
On cubing both sides
`x^(3)+1/(x^(3))+3x xx 1/x(x+1/x)=27`
`implies x^(3)+1/(x^(3))+3xx3=27`
`x^(3)+1/(x^(3))=18`
`:. (x^(3)+1/(x^(3)))(x^(2)+1/(x^(2)))=18xx7`
`(x^(5)+1/(x^(5)))+(x+1/x)+126`
`(x^(5)+1/(x^(5))+3=126`
`=(x^(5)+1/(x^(5)))=123`
554.

यदि `x=sqrt(3)+sqrt(2)` है तो `(x^(3)+1/(x^(3)))` का मान ज्ञात करें।A. `6sqrt(3)`B. `12sqrt(3)`C. `18sqrt(3)`D. `24sqrt(3)`

Answer» Correct Answer - C
`x=sqrt(3)+sqrt(2)`
`:. 1/x=sqrt(3)-sqrt(2)`
`x^(3)+1/(x^(3))`
`:. x^(3)=(sqrt(3)+sqrt(2))^(3)`
`=(sqrt(3))^(3)+(sqrt(2))^(3)+3xxsqrt(3)xxsqrt(2)(sqrt(3)+sqrt(2))`
`=3sqrt(2)+2sqrt(2)+3sqrt(6)(sqrt(3)+sqrt(2))`
`=3sqrt(3)+2sqrt(2)+9sqrt(2)+6sqrt(3)`
`x^(3)=9sqrt(3)+11sqrt(2)`
`1/(x^(3))=9sqrt(3)-11sqrt(2)`
`x^(3)+1/(x^(3))=9sqrt(3)+11sqrt(2)+9sqrt(3)-11sqrt(2)`
`=18sqrt(3)`
Alternate:
`x=sqrt(3)+sqrt(2)`
`1/x=sqrt(3)-sqrt(2)`
and `x+1/x=sqrt(3)+sqrt(2)+sqrt(3)-sqrt(2)`
`=2sqrt(3)`
`x^(3)+1/(x^(3))=(x+1/x)^(3)-3(x+1/x)`
`=(2sqrt(3))^(3)-3(2sqrt(3))`
`=24sqrt(3)-6sqrt(3)=18sqrt(3)`
555.

यदि `x` वास्तविक संख्या है तो `x+1/x!=0` और `x^(3)+1/(x^(3))=0` है तो `(x+1/x)^(4)` का मान ज्ञात करें।A. 4B. 9C. 16D. 25

Answer» Correct Answer - B
`x^(3)+1/(x^(3))=0`
`(x+1/x)^(3)-3x xx 1/x(x+1/x)=0`
`(x+1/x)^(3)-3(x+1/x)=0`
`(x+1/x)^(3)=3(x+1/x)`
`(x+1/x)^(2)=3`
`((x+1/x)^(2))^(2)=(3)^(2)`
`(x+1/x)^(1)=9`
556.

यदि `a**b=2a-3b+ab` है तो `3**5+5**3` किसके बराबर होगा?A. 22B. 24C. 25D. 28

Answer» Correct Answer - A
`3**5+5**3`
`implies3**5=2xx3-3xx5+3xx5`
`=6-15+15=6`
`implies 5**3=2xx5-3xx3+3xx5`
`=10-9+15=16`
`:. 3**5+5**3`
`implies6+16=22`
557.

यदि `(p-q)` का `5%=(p+q)` का `30%` है तो `p:q` किसके बराबर है?A. `5:3`B. `4:1`C. `3:5`D. `1:4`

Answer» Correct Answer - B
`50% (p-q)=30%(p+q)`
`(p-q)/2=3/10(p+q)`
`[50%=1/2]`
`implies 5(p-q)=3(p+q)`
`implies5p-5q=3p+3q`
`implies 2p=8q`
`implies1p=4q`
`p:q`
`implies4:1`
558.

यदि `(a^(2)+b^(2))^(3)=(a^(3)+b^(3))^(2)` है तो `a/b+b/a=?`A. `1/3`B. `2/3`C. `-1/3`D. `-2/3`

Answer» Correct Answer - B
`(a^(2)+b^(2))^(3)=(a^(3)+b^(3))^(2)`
`implies a^(6)+b^(6)+3a^(2)b(a^(2)+b^(2))=a^(6)+`
`b^(6)+2a^(3)b^(3)`
`implies a^(6)+b^(6)+3a^(4)b^(2)+3a^(2)b^(4)=a^(6)+`
`b^(6)+2a^(3)b^(3)`
`implies 3a^(4)b^(2)+3a^(2)b^(4)=2a^(3)b^(3)`
`implies a^(2)b^(2)(3a^(2)+3b^(2))=2a^(3)b^(3)`
`3a^(2)+3b^(2)=2ab`
`3(a^(2)+b^(2))=2ab`
`implies(a^(2)+b^(2))/(ab)=2/3`
`implies a/b+b/a=2/3`
559.

यदि `2x+2/x=3` है तो `x^(3)+1/(x^(3))+2` का मान ज्ञात करें।A. `-9/8`B. `-25/8`C. `7/8`D. `11`

Answer» Correct Answer - C
`2x+2/x=3`
`implies x+1/x=3/2`
Taking cube on the sides
`=(x+1/x)^(3)=(3/2)^(3)`
`{:|((x+1/x=a),(x^(3)+1/(x^(3))=a^(3)-3a)):}`
`x^(3)+1/(x^(3))+3(x+1/x)=27/8`
`implies x^(3)+1/(x^(3))+3xx3/2=27/8`
`implies x^(3)+1/(x^(3))=27/8-9/2`
`=(27-36)/8=(-9)/8`
`:. x^(3)+1/(x^(3))+2=(-9)/8+2`
`=x^(3)+1/(x^(3))+2=(-9+16)/8=7/8`
560.

यदि `a+b+c=0` है तो `(a^(2)+b^(2)+c^(2))/(a^(2)-bc)` का मान क्या होगा?

Answer» Correct Answer - C
`a+b+c=0`
Assume values `a=2, b=-2, c=0`
`a+b+c=2-2+0=0` (satisfy)
`:. (a^(2)+b^(2)+ c^(2))/(a^(2)-bc)`
`implies (4+4+0)/(4-0)implies8/4=2`
Alternate
`a+b+c=0`
`b+c=-a`
Squaring both sides
`(b+c)^(2)=a^(2)`
`b^(2)+c^(2)+2bc=a^(2)`
`b^(2)+c^(2)=a^(2)-2bc`
`:. (a^(2)+b^(2)+c^(2))/(a^(2)-bc)`
`implies (a^(2)+a^(2)-2bc)/(a^(2)-bc)`
`= (2a^(2)-2bc)/(a^(2)-bc)implies(2(a^(2)-bc))/(a^(2)-bc)=2`
561.

यदि `a+1/b=1` और ` b+1/c=1` है तो `c+1/a` किसके बराबर है?

Answer» Correct Answer - C
`a+1/b=1, b+1/c=1,c+1/a=?`
Put values,
`a=1/2 b=2 c=-1`
`c+1/a=-1+1/((1/2))=-1+2=1`
Alternate
`implies a+1/b=1`……………….(i)
`impliesa=1-1/b=(b-1)/b`
`1/a=b/(b-1)impliesb+1/c=1`
`1/c=1-b, c=1/(1-b)`
`:. c+1/a=1/(1-b)+b/(b-1)`
`1/(1-b)-b/(1-b)=(1-b)/(1-b)=1`
562.

यदि `(sqrt(7)-2)/(sqrt(7)+2)=asqrt(7)+b` है तो `a` का मान ज्ञात करें?A. `11/3`B. `-4/3`C. `4/3`D. `(-4sqrt(7))/3`

Answer» Correct Answer - B
`(sqrt(7)-2)/(sqrt(7)+2)=asqrt(7)+b`
L.H.S `=(sqrt(7)-2)/(sqrts(7)+2)xx(sqrt(7)-2)/(sqrt(7)-2)`
(Rationalisation)
`=((sqrt(7)-2)^(2))/((sqrt(7))^(2)-(4))=(7+4-4sqrt(7))/(7-4)`
`implies (11-4sqrt(7))/3`
`11/3-4/3sqrt(7)=-4/3sqrt(7)+11/3`
`=a sqrt(7)+11/3`
`=asqrt(7)+b=` R.H.S
Compare the cofficients of `sqrt(7)` and constant term
`a=-4/3`
`b=11/3`
563.

`a+b+c=0` है `1/((a+b)(b+c))+1/((a+c)(b+a))+1/((c+a)(c+b))` का मान ज्ञात करें?A. 1B. 0C. `-1`D. `-2`

Answer» Correct Answer - B
`a+b+c=0`
`1/((a+b)(b+c))+1/((a+c)(b+a))+`
`1/((c+a)(c+b))`
`implies((a+c)+(b+c)+(a+b))/((a+b)(a+c)(b+c)`
`implies (2(a+b+c))/((a+b)(a+c)(b+c))=0`
`( :. a+b+c=0)`
564.

यदि `a^(2)+b^(2)+2b+4a+5=0` है तो `(a-b)/(a+b)` का मान ज्ञात करें।A. `3`B. `-3`C. `1/3`D. `-1/3`

Answer» Correct Answer - C
`a^(2)+b^(2)+2b+4a+5=0`
`a^(2)+b^(2)+2b+4a+4+1=0`
`a^(2)+4a+4+b^(2)+2b+1=0`
`(a+2)^(2)+(b+1)^(2)=0`
`a+2=0, a=-2`
`b+1=0, b=-1`
`(a-b)/(a+b)implies(-2+1)/(-2-1)`
`implies (-1)/(-3)=1/3`
565.

यदि `x+y+z=0` है तो `(x^(2))/(yz)+(y^(2))/(zx)+(z^(2))/(xy)=?`A. `(xyz)2`B. `x^(2)+y^(2)+z^(2)`C. `9`D. `3`

Answer» Correct Answer - D
`(x^(2))/(yz)+(y^(2))/(zx)+(z^(2))/(xy)`
`=(x^(2))/(yz)xx x/x +(y^(2)xxy)/(zx xxy)+(z^(2))/(xy)xx z/z`
`= (x^(3)+y^(3)+z^(3))/(xyz)`
`( :.` If `x+y+z=0` then `x^(3)+y^(3)+z^(3)implies3xyz)`
`:.(3xyz)/(xyz)=3`
566.

यदि `a^(2x+2)=1` जहां `a,1` के अतिरिक्त एक धनात्मक वास्तविक संख्या है तो `x` किसके बराबर है?A. `-2`B. `-1`C. `0`D. `1`

Answer» Correct Answer - B
`a^(2x+2)=1`
`a^(2x+2)=a^(0)`
`2x+2=0`
`x=-2/2=-1`
567.

यदि `a+1/a+1=0(a!=0)` है तो `(a^(4)-a)` का मान क्या होगा?

Answer» Correct Answer - A
`a+1/a=1=0`
`a+1/a=-1`
Squaring both sides
`implies a^(2)+1/(a^(2))+2=1`
`impliesa^(2)+1/(a^(2))=-1`
`impliesa^(2)+1=(-1)/(a^(2))`……………i
`impliesa+1/a=-1` (given)
`:.a^(2)+1=-a` ………….ii
`implies-a=(-1)/(a^(2))`
From equation i and ii
`a^(3)=1`
`:. a^(3)-1=0`
`impliesa^(4)-a=a(a^(3)-1)=axx0=0`
568.

यदि `ax+by=1` और `bx+ay=(2ab)/(a^(2)+b^(2))` हो तो `(x^(2)+y^(2))(a^(2)+b^(2))` किसके बराबर है?A. 1B. 2C. 0.5D. 0

Answer» Correct Answer - A
`ax+by=1`
`bx+ay=(2ab)/(a^(2)+b^(2))`
Let `a=b=1`
then `x+y=1` …………i
`x+y=(2xx1xx1)/(1+1)=1`………..ii
Now put
`x=y=1/2` in eq i and ii
`1/2+1/2=1`
and equation ii
`1/2+1/2=1`
Value of `(x^(2)+y^(2))(a^(2)+b^(2))`
`=(1/2)^(2)+(1/2)^(2)(1+1)`
`=(1/4+1/4)xx2=2/4xx2=1`
569.

यदि `(3a+5b)/(3a-5b)=5` है तो `a:b` किसके बराबर है ?A. `2:1`B. `2:3`C. `1:3`D. `5:2`

Answer» Correct Answer - D
`(3a+5b)/(3a-5b)=5`
`implies 3a+5b=15a-25b`
`implies12a=30b`
`implies 2a=5b`
`a:b`
`5:2`
570.

यदि `a+1/b=b+1/c=c+1/a` जहां `a!=b!=c` तो `abc` किसके बराबर है?A. `+1`B. `-1`C. `+1` & `-1`D. इनमें से कोई नहीं

Answer» Correct Answer - C
`a+1/b=b+1/c=c+1/a`
Put `a=1/2,b=2, c=-1`
`1/2+1/2=2-1=-1+2`
`1=1=1`
`abc=-1/2xx2x-1`
`abc=-1`
again put
`a=-1/2,b=-2,c=1`
`a+1/b=b+1/c+c+1/a`
`-1/2-1/2=-2+1=1-2`
`-1=-1=-1`
equation satisfied
`abc=-1/2xx-2xx1=1`
So abc can be `-1` and `+1`
571.

यदि `a+b+c=2s`, तो `((s-a)^(2)+(s-b)^(2)+(s-c)^(2)+s^(2))/(a^(2)+b^(2)+c^(2))` किसके बराबर है?A. `a^(2)+b^(2)+c^(2)`B. `0`C. `1`D. `2`

Answer» Correct Answer - C
`a+b+c=2s`
`:.` Let
`a=2`
`b=1`
`c=1`
`s=2`
`:. ((s-a)^(2)+(s-b)^(2)+(s-c)^(2)+s^(2))/(a^(2)+b^(2)+c^(2))`
`implies ((2-2)^(2)+(2-1)^(2)+(2-1)^(2)+2^(2))/(2^(2)+1^(2)+1^(2))`
`implies (0+1+1+4)/(4+1+1)=6/6=1`
572.

यदि `x=a+1/a` और `y=a-1/a` है तो `x^(4)+y^(4)2x^(2)y^(2)` का मान ज्ञात करें?A. 214B. 18C. 16D. 12

Answer» Correct Answer - C
`x=a+1/a`
`y=a-1/a`
`:. (x+y)=a+1/a+a-1/a=2a`
`:. (x-y)=a+1/a-a+1/a=2/a`
`:.x^(4)+y^(4)-2x^(2)y^(2)-(x^(2)-y^(2))^(2)`
`implies ((x+y)(x-y))^(2)`
`implies (2a xx 2/a)^(2)`
`=(4)^(2)=16`
573.

यदि `1ltxlt2` है तो `sqrt((x-1)^(2))+sqrt((x-3)^(2))` का मान क्या होगा?A. 1B. 2C. 3D. `2x-4`

Answer» Correct Answer - B
`1ltxlt2`
`sqrt((x-1)^(2))+sqrt((3-x)^(2))`
(square root cancel with square)
`:. x-1+3-x=2`
574.

यदि `x=19` और `y=18` है तो `(x^(2)+y^(2)+xy)/(x^(3)-y^(3))` का मान ज्ञात करें?A. 1B. 37C. 324D. 361

Answer» Correct Answer - A
`x=19 y=18`
`(x^(2)+y^(2)+xy)/(x^(3)-y^(3))`
`=(x^(2)+y^(2)+xy)/((x-y)(x^(2)+y^(2)+xy))`
`=1/(x-y)=1/(19-18)=1`
575.

यदि `a=11` और `b=9` है तो `((a^(2)+b^(2)+ab)/(a^(3)-b^(3)))` का मान ज्ञात करें?A. `1/2`B. `2`C. `1/20`D. `20`

Answer» Correct Answer - A
`a=11`
`b=9`
`implies(a^(2)+b^(2)+ab)/(a^(3)-b^(3))`
`implies (a^(3)-b^(3))=(a-b)(a^(2)+ab+b^(2))`
`:. (a^(2)+b^(2)+ab)/((a=b)(a^(2)+ab+b^(2))`
`=1/(a-b)=1/(11-9)=1/2`
576.

यदि `p=101` है तो `root(3)(p(p^(2)-3p+3)-1)` का मान ज्ञात करें?A. 100B. 101C. 102D. 1000

Answer» Correct Answer - A
`p=101`
`=root(3)(p(p^(2)-3p+3)-1)`
`=root(3)(p^(3)-3p^(2)+3p-1)`
`:.[(p-1)^(3)=p^(3)-(1)^(3)-3p(p-1)]`
`=root(3)((p-1)^(3))`
`=p-1=101-1=100`
577.

यदि `c+1/c=3`, हो तो `(c-3)^(7)+1/(c^(7))` का मान क्या है?A. 2B. 0C. 3D. 1

Answer» Correct Answer - B
`C+1/C=3`
`C-3+1/C=0`
So `(C-3)^(7)+1/(C^(7))=[(C-3)+1/C]^(3)`
`[(C-3)+1/C]^(4)-[(C-3)+1/C]=0`
578.

The total quantity of water contained in two vessels was 16 litres. When 3 litres of water was poured from one vessel to the other vessel, both the vessels were found containing equal quantities of water. Then what was the difference between the quantities of water contained in the two vessels initially?1. 42. 53. 64. 7

Answer» Correct Answer - Option 3 : 6

Given:

The total quantity of water = 16 litres

3 litres of water was poured from one vessel to the other vessel, both the vessels were found containing equal quantities of water

Calculation

Let the quantity of water in two vessels be 'x' and 'y' respectively

So, x + y = 16

When 3 litres if poured from one vessel to the other we get,

 x - 3 = y + 3 (since 3 is removed from x and added to y, also given that they are equal)

⇒ x - y = 6

∴ Difference between the quantities of water in litres = 6 

579.

In the given question, two equations numbered l and II are given. Solve both the equations and mark the appropriate answer.I. x2 + 2x –15 = 0 II. y2 + 9y + 20 = 01. y > x2. y

Answer» Correct Answer - Option 5 : x = y or the relationship between x and y cannot be established.

Calculation:

I. x2 + 2x –15 = 0 

⇒ x2 + 5x –3x –15 = 0

⇒ x × (x + 5) –3 × (x + 5) = 0

⇒ (x – 3) × (x + 5) = 0

⇒ x = 3 and x = –5

II. y2 + 9y + 20 = 0

⇒ y2 + 5y + 4y + 20 = 0

⇒ y × (y + 5) + 4 × (y + 5) = 0

⇒ (y + 4) × (y + 5) = 0

⇒ y = –4 and y = –5

Value of x

Value of y

Relation

3

 −4

x > y

−5

−5

x = y

3

−5

x > y

−5

−4

x < y


∴ x = y or the relationship between x and y cannot be established.

580.

In the given question, two equations numbered l and II are given. You have to solve both the equations and mark the appropriate answer-I. x2 = 4II. y2 - 6y + 8 = 01. x > y2. x ≥ y3. x < y4. x ≤ y5.  x = y or the relation cannot be determined

Answer» Correct Answer - Option 4 : x ≤ y

Given:

I. x2 = 4

II. y2 – 6y + 8 = 0

Concept used:

Using factorization method.

Calculation:

x2 = 4

⇒ x2 – 4 = 0

⇒ (x – 2)(x + 2) = 0

⇒ (x – 2) = 0 or (x + 2) = 0

⇒ x = 2 or x = -2

⇒ x = -2, 2

y2 – 6y + 8 = 0

⇒ y2 – 4y – 2y + 8 = 0

⇒ y(y – 4) – 2(y – 4) = 0

⇒ (y – 4)(y – 2) = 0

⇒ (y – 4) = 0 or (y – 2) = 0

⇒ y = 4 or y = 2

⇒ y = 2, 4

x ≤ y.

Comparison between x and y (via Tabulation):

Value of xValue of yRelation
22x = y
24x < y
-24x < y
-22x < y

 x ≤ y.
581.

In the given questions, two equations numbered l and II are given. You have to solve both the equations and mark the appropriate answerI. 12x2 – 46x + 14 = 0II. 14y2 – 46y + 12 = 01. x > y2. x ≤ y3. x = y or the relationship cannot be established.4. x ≥ y5. x < y

Answer» Correct Answer - Option 3 : x = y or the relationship cannot be established.

I. 12x2 – 46x + 14 = 0

⇒ 12x2 – 42x – 4x + 14 = 0

⇒ 6x(2x – 7) – 2(2x – 7) = 0

⇒ (2x – 7)(6x – 2) = 0

⇒ x = 7/2 or 1/3

II. 14y2 – 46y + 12 = 0

⇒ 14y2 – 42y - 4y + 12 = 0

⇒ 14y(y – 3) – 4(y – 3) = 0

⇒ (y – 3) × (14y – 4) = 0

⇒ y = 3 or 2/7

Comparison between x and y (via Tabulation):

Value of x

Relation

Value of y

7/2

3

7/2

2/7

1/3

3

1/3

2/7

∴ The relationship cannot be established between x and y.

582.

In the given questions, two equations numbered l and II are given. You have to solve both the equations and mark the appropriate answerI. 8x2 – 32x + 14 = 0II. 3y2 – 37y – 26 = 01.x &gt; y2. x ≤ y3. x = y or the relationship cannot be established.4. x ≥ y5. x < y

Answer» Correct Answer - Option 3 : x = y or the relationship cannot be established.

I. 8x2 – 32x + 14 = 0

⇒ 8x2 – 28x – 4x + 14 = 0

⇒ 4x(2x – 7) – 2(2x – 7) = 0

⇒ (2x – 7)(4x – 2) = 0

⇒ x = 7/2 or 1/2

II. 3y2 – 37y – 26 = 0

⇒ 3y2 – 39y + 2y – 26 = 0

⇒ 3y(y – 13) + 2(y – 13) = 0

⇒ (y – 13)(3y + 2) = 0

⇒ y = 13 or -(2/3)

Comparison between x and y (via Tabulation):

Value of x

Relation

Value of y

7/2

13

7/2

-(2/3)

1/2

13

1/2

-(2/3)

∴ Relationship cannot be established between x and y.

583.

In the given questions, two equations numbered l and II are given. You have to solve both the equations and mark the appropriate answer.I. 2x2 – 32x + 128 = 0II. 2y2 – 32y + 96 = 01. x > y2. x ≥ y3. x < y4. x ≤ y5. x = y or the relationship cannot be established.

Answer» Correct Answer - Option 5 : x = y or the relationship cannot be established.

I. 2x2 – 32x + 128 = 0

⇒ 2x2 – 16x – 16x + 128 = 0

⇒ 2x(x – 8) – 16(x – 8) = 0

⇒ (x – 8)(2x – 16) = 0

⇒ x = 8

II. 2y2 – 32y + 96 = 0

⇒ 2y2 – 24y – 8y + 96 = 0

⇒ 2y(y – 12) – 8(y – 12) = 0

⇒ (y – 12)(2y – 8) = 0

⇒ y = 12 or 4

Comparison between x and y (via Tabulation):

Value of x

Relation

Value of y

8

4

8

 <

12

 

Relationship cannot be established between x and y.

584.

In the given question, two equations numbered l and II are given. Solve both the equations and mark the appropriate answer.I. 3x2 + 2x – 1 = 0II. 11y2 + 18y + 7 = 0 1. x &gt; y2. x &lt; y3. x ≥ y4. x ≤ y5. x = y or the relationship between x and y cannot be established.

Answer» Correct Answer - Option 5 : x = y or the relationship between x and y cannot be established.

Calculation:

From I,

3x 2 + 2x – 1 = 0

⇒ 3x2 + 3x – x – 1 = 0

⇒ 3x(x + 1) – 1(x + 1) = 0

⇒ (3x – 1)(x + 1) = 0

Taking, 

⇒ 3x – 1 = 0 or x + 1 = 0

⇒ x = 1/3 or x = –1

 

From II,

11y2 + 18y + 7 = 0 

⇒ 11y2 + 11y + 7y +7 = 0

⇒ 11y(y + 1) + 7(y + 1) = 0

⇒ (y + 1)(11y + 7) = 0

Taking, 

⇒ y + 1 = 0 or 11y + 7 = 0

⇒ y = –1 or y = –7/11

Comparison between x and y (via Tabulation)

Value of x

Value of y

Relation

1/3

–1

x > y

1/3

–7/11

x > y

–1

–1

x = y

–1

–7/11

x < y

 

∴x = y or the relationship between x and y cannot be established. 

585.

In the given questions, two equations numbered l and II are given. You have to solve both the equations and mark the appropriate answer.I. x2 – 3x – 10 = 0II. y2 – 18y + 45 = 0 1. x &gt; y2. x &lt; y3. x ≥ y4. x ≤ y5. x = y or the relationship between x and y cannot be established.

Answer» Correct Answer - Option 5 : x = y or the relationship between x and y cannot be established.

Calculation:

From I,

2 – 3x – 10 = 0

⇒ x2 – 5x + 2x – 10 = 0

⇒ x(x – 5) + 2(x – 5) = 0

⇒ (x – 5)(x + 2) = 0

Taking, 

⇒ x – 5 = 0 or x + 2 = 0 

⇒ x = 5 or x = -2

 

From II,

y2 – 18y + 45 = 0 

⇒ y2 – 15y – 3y + 45 = 0

⇒ y(y – 15) – 3(y – 15) = 0

⇒ (y – 15) (y – 3) = 0 

Taking, 

⇒ y – 15 = 0 or y – 3 = 0

⇒ y = 15 or y = 3

Comparison between x and y (via Tabulation)

Value of x

Value of y

Relation

5

15

x < y

5

3

x > y

-2

15

x < y

-2

3

x < y

 

∴ x = y or the relationship between x and y cannot be established. 

586.

A man buys 2 apples and 3 kiwi fruits for Rs. 37. If he buys 4 apples and 5 kiwi fruits for Rs. 67, then what will be the total cost of 1 apple and 1 kiwi fruit?1. Rs. 152. Rs. 283. Rs. 184. Rs. 20

Answer» Correct Answer - Option 1 : Rs. 15

Given

A man buys 2 apples and 3 kiwi = Rs.37

He buys 4 apples and 5 Kiwi for Rs.67

Concept used

We solve these type of question by equation method

Calculation

Let the price of 1 apple be  Rs.x

Let the price of 1 Kiwi be Rs.y

According to question

∴ Price of 2 apples and 3 kiwi

⇒ 2x + 3y = Rs.37      ----(1)

⇒ Price of 4 Apples and 5 Kiwi

⇒ 4x + 5y = Rs.67      ----(2)

⇒ Multiply equation (1) by 2 and then subtract it from equation (2), we get

⇒ y = Rs.7

⇒  put the value of y in equation (1), we get

⇒ 2x = 37- 21

⇒ x = Rs.8

∴ price of 1 apple and 1 kiwi

⇒ 8 + 7 

⇒ Rs.15

 

587.

In the given question, two equations numbered I and II are given. Solve both the equations and mark the appropriate answer.I.  7x2 + 15x + 8 = 0II.  y2 + y/2 – 1/2 = 01. x > y2. x < y3. x ≥ y4. x ≤ y5. x = y or the relationship between x and y cannot be established.

Answer» Correct Answer - Option 4 : x ≤ y

I. 7x2 + 15x + 8 = 0

⇒ 7x2 + 7x + 8x + 8 = 0

⇒ 7x(x + 1) + 8(x + 1) = 0

⇒ (7x + 8)(x + 1) = 0

⇒ x = -8/7, -1

II. y2 + y/2  – 1/2 = 0

⇒ y2 + y – 1/2y – 1/2 = 0

⇒ y(y + 1) – 1/2(y + 1) = 0

⇒ (y – 1/2)(y + 1) = 0

⇒ y = 1/2, -1

Value of x

Value of y

Relation

-8/7

1/2

X < y

-8/7

-1

X < y

-1

1/2

X < y

-1

-1

X = y

∴ x ≤ y

588.

Umesh goes on a tour of three cities of Malaysia. In every city, he spends Rs. 40 more than 1/4th of the money he has with him. At the end of the tour, Umesh has only Rs. 16400 left with him. Find the amount with him before he started the tour of Malaysia.1. Rs. 386722. Rs. 443513. Rs. 354364. Rs. 389815. Rs. 38781

Answer» Correct Answer - Option 4 : Rs. 38981

Calculation:

Let the amount with Umesh, before he started the trip to Malaysia be x.

In the first city he spends = x/4 + 40

He would be left with = x – (x/4 + 40)

⇒ 3x/4 – 40

In the second city he spends = ¼(3x/4 - 40) + 40

⇒ 3x/16 + 30

He would be left with = (3x/4 - 40) – (3x/16 + 20)

⇒ 9x/16 – 60

In the third city he spends = ¼(9x/16 - 60) + 40

⇒ 9x/64 + 15

He would be left with = (9x/16 - 60) – (9x/64 + 15)

⇒ 27x/64 – 45

∴ total amount left with him = 16400

⇒ 27x/64 – 45 = 16400

⇒ 27x/64 = 16445

⇒ x = (16445 × 64)/27

⇒ x = 38980.74 ≈ Rs. 38,981

The amount with Umesh before he started the tour of Malaysia is Rs. 38,981.

589.

Ambani bought a total of 30 Aircraft, Lamborghini, and Bentley for Rs.136 million. He bought one Lamborghini more than Bentley. The cost of each Aircraft was Rs. 8 million each, Lamborghini was Rs. 3 million each and Bentley was Rs. 4 million each. How many Aircraft did he buy?1. 72. 63. 84. 95. 5

Answer» Correct Answer - Option 1 : 7

Calculation:

Let the number of Aircraft, Lamborghini and Bentley bought by Ambani be x, y, and z respectively.

According to the question:

x + y + z = 30      ----(i)

8x + 3y + 4z = 136      ----(ii)

From (ii) – (i) × 4, we get

4x – y = 16      ----(iii)

From (iii)

When y = 0 then x = 4

∴ z = (30 – 4 - 0)

⇒ z = 26

The other solutions are obtained by adding 1 repeatedly to x.

When x = 5 then y = 4

∴ z = (30 – 5 - 4)

⇒ z = 21

When x = 6 then y = 8

∴ z = (30 – 6 - 8)

⇒ z = 16

When x = 7 then y = 12

∴ z = (30 – 7 - 12)

⇒ z = 11

When x = 8 then y = 16

∴ z = (30 – 8 - 16)

⇒ z = 6

When x = 9 then y = 20

∴ z = (30 – 9 - 20)

⇒ z = 1

When x = 10 then y = 34

∴ z = (30 – 10 - 34)

⇒ z = -14

This is not possible.

Calculate results in a table.

X

4

5

6

7

8

9

Y

0

4

8

12

16

20

Z

26

21

16

11

6

1


Since he bought at least one of each thing and one more Lamborghini than Bentley.

So, 4th combination is the right combination.

No. of Aircrafts = 7 ; No. of Lamborghinis = 12 ; No. of Bentleys = 11

Ambani bought 7 Aircraft.

590.

The value of \(\frac{1}{{(7\; + \;4\sqrt 3 })^2} + \frac{1}{{(7\; - \;4\sqrt 3 )^2}}\) is1. 1942. 1543. 1844. 149

Answer» Correct Answer - Option 1 : 194

Given:

\(\frac{1}{{(7\; + \;4√ 3 })^2} + \frac{1}{{(7\; - \;4√ 3 )^2}}\)

Concept used:

Componendo and dividendo

Calculation:

\(\frac{1}{{(7\; + \;4√ 3 })^2} + \frac{1}{{(7\; - \;4√ 3 )^2}}\)

⇒ \(\frac{(7\; - \;4√3)^2}{{(7\; + \;4√ 3 })^2(7\; - \;4√3)^2} + \frac{(7\; + \;4√3)^2}{{(7\; - \;4√ 3 )^2(7 \;+\;4√3)^2}}\)

⇒ \(\frac{(7\; - \;4√3)^2}{{1}} + \frac{(7\; + \;4√3)^2}{1}\)

⇒ 72 + (4√3)2 – 2 × 7 × 4√3 + 72 + (4√3)2​ + 2 × 7 × 4√3

⇒ 49 + 48 – 56√3 + 49 + 48 + 56√3

⇒ 49 + 48 + 49 + 48

⇒ 194

∴ Required value is 194

591.

If a2 + b2 = 2a + 4b – 5, then what is the value of (a + b)?1. 52. 43. 24. 3

Answer» Correct Answer - Option 4 : 3

Given:

a2 + b2 = 2a + 4b  5

Formula used:

(a – b)2 = a2 + b2 – 2ab

Calculation:

a2 + b2 = 2a + 4b  5

⇒  a2 + b2  2a  4b + 5 = 0

⇒  a2 + b2  2a  4b + 1 + 4 = 0

⇒  (a2  2a + 1) + (b2  4b  + 4) = 0

⇒ (a – 1)2 + (b – 2)2 = 0 

The above expression is possible only when,

(a – 1) = 0, (b – 2) = 0 

⇒ a = 1, b = 2

a + b = 1 + 2 = 3

∴ The value of a + b is 3

592.

If (a2 – b2) = 30, a – b = 6 then, what is the value of a + b?1. 72. 93. 54. 12

Answer» Correct Answer - Option 3 : 5

Given:

(a2  b2) = 30

a – b = 6

Formula required:

(a + b)(a – b) = a2 – b2

Calculations:

(a + b) × 6 = 30

⇒ (a + b) = 30/6

⇒ (a + b) = 5

∴ The value of (a + b) is 5

593.

If x + y + z = 5, x2 + y2 + z2 = 21 and y2 = zx, then the value of y is:1.  1/52. 2/53. 1/24. 1/4

Answer» Correct Answer - Option 2 : 2/5

Given:

x + y + z = 5

x2 + y2 + z2 = 21

y2 = zx

Formula used:

(x + y + z)2 = x2 + y2 + z2 + 2(xy + yz + xz)

Calculations:

(x + y + z)2 = 52

⇒ x2 + y2 + z2 + 2(xy + yz + xz) = 25

⇒ 21 + 2(xy + yz + xz) = 25

⇒ 2(xy + yz + xz) = 25 - 21

⇒ xy + yz + xz = 4/2

⇒ xy + yz + xz = 2

⇒ xy + yz+ y2 = 2

⇒ y(x + y + z) = 2

⇒ y(5) = 2

⇒ y = 2/5

∴ The required value of y = 2/5

594.

The cost of 4 pencil and 5 pen is Rs 47 and cost of 2 pencil and 7 pen is Rs. 55, then what is the cost of the one pencil?1. Rs. 52. Rs. 33. Rs. 74. Rs. 8

Answer» Correct Answer - Option 2 : Rs. 3

Given:

The cost price of 4 pencils and 5 pens = 47

The cost price of 2 pencils and 7 pens = 55

Calculation:

Let the cost price of pencil be 'x' and pen be 'y'

4x + 5y = 47       ------(1)

2x + 7y = 55      -------(2)

Now, 2 × eq (2) – eq (1)

2(2x + 7y) – (4x + 5y) = 2 × 55 – 47

⇒ 4x + 14y – 4x – 5y = 110 – 47

⇒ 9y = 63

⇒ y = 7

Substituting the value of y in eq (1) then,

⇒ 4x + 5 × 7 = 47

⇒ 4x = 47 – 35

⇒ 4x = 12

⇒ x = 3 

∴ The cost price of one pencil is Rs. 3

595.

If a3 + b3 = 62 and a + b = 2, then the value of ab is:1. -62. 93. 64. -9

Answer» Correct Answer - Option 4 : -9

Given:

a + b = 2

a3 + b3 = 62

Formula used:

(a + b)3 = a3 + b3 + 3ab(a + b)

Calculation:

a + b = 2

Cubing the given equation

(a + b)3 = 23

⇒ a3 + b3 + 3ab(a + b) = 8      ----[(a + b)3 = a3 + b3 + 3ab(a + b)]

⇒ 62 + 3ab × 2 = 8      ----(a3 + b3 = 62, a + b = 2)

⇒ 6ab = 8 – 62

⇒ 6ab = -54

⇒ ab = -54/6 = -9

∴ The value of ab is -9.

596.

18x2 – 12x – 2y + 3xy = 1. (6x + y)(3x – 2)2. (6x – y)(3x – 2)3. (3x – y)(6x + 2)4. (3x + y)(6x – 2)

Answer» Correct Answer - Option 1 : (6x + y)(3x – 2)

Calculation:

18x2 – 12x – 2y + 3xy

⇒ 6x(3x – 2) + y( 3x – 2)

⇒ (6x + y) (3x – 2)

∴ The required answer is (6x + y) (3x – 2)

597.

If \(x=\frac{{\sqrt 3 }}{2}\), then the value of \(\frac{{\sqrt {1 + x} + \sqrt {1 - x} }}{{\sqrt {1 + x} - \sqrt {1 - x} }}\) is equal to:1. √22. √33. 34. 2

Answer» Correct Answer - Option 2 : √3

Calculation:

\({√(1 + x) + √(1 – x)}\over{√(1 + x) – (√1 – x)}\) × \({√(1 +x) + √(1 – x)}\over {√(1 + x) + √(1 – x)}\)

\((1 + x) + (1 – x) + 2√(1 – x^2) \over(1 + x) – (1 – x)\)

\(2 + 2√(1 – (√3/2)^2)\over2x\)

\(2 + 2 × (1/2)\over 2 × (√3/2) \)

⇒ (3/√3) × (√3/√3)  

⇒ √3   

598.

If 9x + 7y = 130, 2x – y = 11, then what will be the value of (x + y)?1. 152. 143. 214. 16

Answer» Correct Answer - Option 4 : 16

Given:

9x + 7y = 130    

2x – y = 11    

Calculation:

Our given equation are 

9x + 7y = 130      ----(1)

2x – y = 11      ----(2)

Multiply eq (2) with 7 and equation (1) with 1

9x + 7y = 130      ----(3)

7(2x – y) = 11 × 7 = 77     ----(4)

Add equation (4) and equation (3)

9x + 7y + 14x – 7y = 130 + 77

⇒ 23x = 207

⇒ x = 207/23 = 9

Now, from eq (2)

2x – y = 11

⇒ 2 × 9 – y = 11

⇒ y = 18 – 11 = 7

Now, x + y = 9 + 7 = 16

∴ The required answer is 16

599.

x - 1/x = 5 Find the value of x4 + 1/x41. 7312. 7243. 7274. 745

Answer» Correct Answer - Option 3 : 727

Given:

x - 1/x = 5      ----(1)

Formula Used:

x2 + 1/x2 = (x - 1/x)2 + 2

x2 + 1/x2 = (x + 1/x)2 - 2

Calculation:

x2 + 1/x2 = (x - 1/x)2 + 2

⇒ x2 + 1/x2 = 52 + 2  [Using (1)]

⇒ x2 + 1/x2 = 27      ----(2)

x4 + 1/x4

⇒ (x2)2 + (1/x2)2

⇒ (x2 + 1/x2)2 - 2   [Using (2)]

⇒ (27)2 - 2

⇒ 729 - 2

⇒ 727

600.

(7x + 12)2 – 336x is equal to 1. (7x + 11)22. (7x + 9)23. (7x – 9)24. (7x – 12)2

Answer» Correct Answer - Option 4 : (7x – 12)2

Formula used:

(a + b)2 = a2 + b2 + 2ab

Calculation:

(7x + 12)2 – 336x

⇒ 49x2 + 144 + 168x – 336x

⇒ 49x2 – 168x + 144

⇒ 49x2 – 84x – 84x + 144 

⇒ 7x (7x – 12) – 12(7x –12) 

⇒ (7x – 12)(7x –12) 

⇒ (7x – 12)2

∴ The required answer is  (7x – 12)2