MCQ
If $x({x^4} + 1)\phi (x) = 1,$ then $\int_1^2 {\phi (x)\,dx = } $
  • $\frac{1}{4}\log \frac{{32}}{{17}}$
  • B
    $\frac{1}{2}\log \frac{{32}}{{17}}$
  • C
    $\frac{1}{4}\log \frac{{16}}{{17}}$
  • D
    None of these

Answer

Correct option: A.
$\frac{1}{4}\log \frac{{32}}{{17}}$
a
(a) Here $\phi (x) = \frac{1}{{x({x^4} + 1)}} = \frac{1}{x} - \frac{{{x^3}}}{{{x^4} + 1}}$

==> $\int_1^2 {\phi (x)dx = \int_1^2 {\,\left( {\frac{1}{x} - \frac{{{x^3}}}{{{x^4} + 1}}} \right)} \,dx} $

$ = |\log x|_1^2 - \left| {\frac{1}{4}\log ({x^2} + 1)} \right|_1^2 = \frac{1}{4}\log \frac{{32}}{{17}}$.

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