MCQ
If $y=x \log _e x$ then value of $\frac{d^2 y}{d x^2}$ :
  • A
    $\frac{1}{1+x}$
  • B
    $1+\log _e x$
  • C
    $\log _e(1+x)$
  • $\frac{1}{x}$

Answer

Correct option: D.
$\frac{1}{x}$
(D)Given that $y=x \log _e x$
$\therefore \quad \frac{d y}{d x}=1 \cdot \log x+x \cdot \frac{1}{x}=1+\log _e x$
again differentiating
$\frac{d}{d x}\left(\frac{d y}{d x}\right)=\frac{d}{d x}\left(1+\log _c x\right)=0+\frac{1}{x}=\frac{1}{x}$
$\Rightarrow \quad \frac{d^2 y}{d x^2}=\frac{1}{x}$
Hence correct option is (D).

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free