SarkariPYQ

SSC CGL 2020 PYQ — Question 20

SSC CGL Tier II - Quant - 16 Nov 2020 • Quantitative Aptitude • Q20

Back to paper

If 2x2 - 7x + 5 = 0, then what is the value of x2 + 25/4x2?

Show answer & explanation

Correct answer: B

Explanation

The correct answer is option 2 i.e. 714\frac{1}{4} .

2x2 - 7x + 5 = 0

On dividing both sides by 2x we get,

x - 7/2 + 5/2x = 0

x + 5/2x = 7/2............(1)

On squaring both sides we get,

x2 + 25/4x2 + 2 × x × 5/2x = 49/4

x2 + 25/4x2 = 49/4 - 5 = 29/4

x2 + 25/4x2 =  714\frac{1}{4}.