

InterviewSolution
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Solve the following inequalities.(i) 4n + 7 ≥ 3n + 10, n is an integer(ii) 6(x + 6) ≥ 5(x – 3), x is a whole number.(iii) -13 ≤ 5x + 2 ≤ 32, x is an integer. |
Answer» (i) 4n + 7 ≥ 3n + 10, n is an integer. 4n + 7 – 3n ≥ 3n + 10 – 3n n(4 – 3) + 7 ≥ 3n + 10 – 3n n(4 – 3) + 7 ≥ n (3 – 3) + 10 n + 7 ≥ 10 Subtracting 7 on both sides n + 7 – 7 ≥ 10 – 7 n ≥ 3 Since the solution is an integer and is greater than or equal to 3, the solution will be 3, 4, 5, 6, 7, … n = 3, 4, 5, 6,7, … (ii) 6(x + 6) ≥ 5(x – 3), x is a whole number. 6x + 36 ≥ 5x – 15 Subtracting 5x on both sides 6x + 36 – 5x ≥ 5x – 15 – 5x x (6 – 5) + 36 ≥ x(5 – 5) – 15 x + 36 ≥ -15 Subtracting 36 on both sides x + 36 – 36 ≥ -15 -36 x ≥ -51 The solution is a whole number and which is greater than or equal to -51 ∴ The solution is 0, 1, 2, 3, 4,… x = 0,1,2, 3,4,… (iii) -13 ≤ 5x + 2 ≤ 32, x is an integer. Subtracting throughout by 2 -13 – 2 ≤ 5x + 2 – 2 ≤ 32 – 2 -15 ≤ 5x ≤ 30 Dividing throughout by 5 \(\frac{-15}{5}\) ≤ \(\frac{5x}{5}\) ≤ \(\frac{30}{5}\) – 3 ≤ x ≤ 6 ∴ Since the solution is an integer between -3 and 6 both inclusive, we have the solution As -3, -2, -1,0, 1,2, 3, 4, 5, 6. i.e. x = -3, -2, 0, 1, 2, 3,4, 5 and 6. |
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