Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Relations and Functions

Question:

The least positive integer for which x $4^x+8^{(2/3)(x-2)}-72-4^{x-3/2}≥0$ is non-negative, is ______.

Correct Answer:
4
Explanation:

We have,

$4^x+8^{(2/3)(x-2)}-72-4^{x-3/2}≥0$

$⇒2^{2x}+2^{2x-4}-2^{2x-3}-72≥0$

$⇒2^{2x}+\frac{2^{2x}+}{16}-\frac{2^{2x}+}{8}-72≥0⇒2^{2x-4}≥\frac{24}{5}$

Clearly, 4 is the smallest positive integer satisfying this inequation.