Target Exam

CUET

Subject

-- Applied Mathematics - Section B2

Chapter

Calculus

Question:

If $x=log \, t $ and $y =\frac{1}{t^2}, $ then $\frac{d^2y}{dx^2}$ is :

Options:

$\frac{2}{t^2}$

$\frac{4}{t^2}$

$-\frac{1}{t}$

$-\frac{4}{t^2}$

Correct Answer:

$\frac{4}{t^2}$

Explanation:

The correct answer is Option (2) → $\frac{4}{t^2}$

$x=\log t$ 

$\frac{dx}{dt}=\frac{1}{t}$

and,

$y=\frac{1}{t^2}$

$\frac{dy}{dt}=\frac{-2}{t^3}$

$⇒\frac{dy}{dx}=\frac{-2}{t^2}$

$⇒\frac{d^2y}{dx^2}=\frac{4}{t^3}×\frac{dt}{dx}=\frac{4}{t^2}$