Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Continuity and Differentiability

Question:

$\underset{x→0}{\lim}\frac{\sin(6x^2)}{ln\,\cos(2x^2-x)}$ is equal to:

Options:

12

-12

6

-6

Correct Answer:

-12

Explanation:

$\underset{x→0}{\lim}\frac{\sin(6x^2)}{ln(\cos(2x^2-x))}=\underset{x→0}{\lim}\frac{\cos(6x^2)×12x}{\frac{-\sin(2x^2-x)}{\cos(2x^2-x)}.(4x-1)}$ [Applying L Hospitals Rule]

$=\underset{x→0}{\lim}\frac{1×12×x}{\frac{+\sin(2x^2-x)}{1}×(1)}=12\underset{x→0}{\lim}\frac{(2x^2-x)}{\sin(2x^2-x)×\frac{x}{(2x^2-x)}}=12\underset{x→0}{\lim}\frac{1}{2x-1}=-12$