Target Exam

CUET

Subject

-- Applied Mathematics - Section B2

Chapter

Calculus

Question:

If $x=5\, t^3,y =7\, t^4 ,$ then $\frac{d^2y}{dx^2}$ is equal to :

Options:

$\frac{28}{15}t$

$\frac{28}{15\, t^2}$

$\frac{14}{5\, t^2}$

$\frac{28}{225\, t^2 }$

Correct Answer:

$\frac{28}{225\, t^2 }$

Explanation:

The correct answer is Option (4) → $\frac{28}{225\, t^2 }$

$x=5t^3,y=7t^4$

$\frac{dx}{dt}=15t^2$,  $\frac{dy}{dt}=28t^3$

$\frac{dy}{dx}=\frac{28t^3}{15t^2}=\frac{28t}{15}$

$\frac{d^2y}{dx^2}=\frac{28}{15}×\frac{dt}{dx}=\frac{28}{225\, t^2}$