Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Continuity and Differentiability

Question:

If $x=e^{y+e^{y+e^{y+... \infty}}}$, x > 0, then $\frac{d y}{d x}$ is equal to

Options:

$\frac{x}{1+x}$

$\frac{1}{x}$

$\frac{1-x}{x}$

$\frac{1+x}{x}$

Correct Answer:

$\frac{1-x}{x}$

Explanation:

$x=e^{y+e^{y+e^{y+... \infty}}}$

⇒  $\log x = y + e^{y+e^{y+e^{y+... \infty}}}$

⇒  $\log x = y + x$

differentiating wrt x

$\frac{1}{x} = \frac{dy}{dx} + 1 ⇒ \frac{dy}{dx} = \frac{1-x}{x}$

Option: 3