SSC CGL 2020 PYQ — Question 87

SSC CGL Tier II - Quant - 18 Nov 2020 • Quantitative Aptitude • Q87

If x(3 - 2x\frac{2}{x}) = 3x\frac{3}{x}, then the value of x3 - 1/x3 is equal to:

Show answer & explanation

Correct answer: C

Explanation

The correct answer is option 3 i.e. 6227\frac{62}{27}

Here it is given that,

 x(3 - 2x\frac{2}{x}) = 3x\frac{3}{x}

3x - 2 = 3/x

3x - 3/x = 2

x - 1/x = 2/3

On cubing both sides we get,

x3 - 1/x3 - 3 × x × 1/x (x - 1/x) = 8/27

x3 - 1/x3 - 2 = 8/27

x3 - 1/x3 = 8/27 + 2

x3 - 1/x3 = 62/27.