Loading [MathJax]/jax/output/HTML-CSS/jax.js
Home / Aptitude Tests / Mathematics / If x is a positive r...
If x is a positive real number, find the range of values for...

If x is a positive real number, find the range of values for which 13x + 12 > 14x

A.

0 > -16

B.

x > 0

C.

0 < x < 4

D.

0 < x < 16

Correct answer is D

13x + 12 > 14x

= 2+3x6x > 14x

= 4(2 + 3x) > 6x = 12x2 - 2x = 0

= 2x(6x - 1) > 0 = x(6x - 1) > 0

Case 1 (-, -) = x < 0, 6x -1 < 0

= x < 0, x < 16 = x < 16 (solution)

Case 2 (+, +) = x > 0, 6x -1 > 0 = x > 0, x > 16

Combining solutions in cases(1) and (2)

= x > 0, x < 16 = 0 < x < 16