Look at an inverse function below. $y = \text{cosec}^{-1}(4x^4); \ |4x^4| > 1$. Find $\frac{dy}{dx}$.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → $-\frac{4x^3}{|x^4|\sqrt{16x^8-1}}$ ##
Given, $y = \text{cosec}^{-1}(4x^4); \ |4x^4| > 1$
The derivative of $y = \text{cosec}^{-1}(u)$ is:
$\frac{dy}{du} = -\frac{1}{|u| \sqrt{u^2 - 1}}$
Let $u = 4x^4$
$\frac{du}{dx} = 16x^3$
Substitute $u$ into $\frac{dy}{du}$: For $u = 4x^4$:
$\frac{dy}{du} = -\frac{1}{4|x^4| \sqrt{16x^8 - 1}}$
Apply the chain rule:
$\frac{dy}{dx}=\frac{dy}{du}.\frac{du}{dx}$
$=-\frac{1}{4|x^4|\sqrt{16x^8-1}}.16x^3$
$\frac{dy}{dx}=-\frac{4x^3}{|x^4|\sqrt{16x^8-1}}$