MCQ
Integrating factor of equation $({x^2} + 1)\frac{{dy}}{{dx}} + 2xy = {x^2} - 1$ is
  • ${x^2} + 1$
  • B
    $\frac{{2x}}{{{x^2} + 1}}$
  • C
    $\frac{{{x^2} - 1}}{{{x^2} + 1}}$
  • D
    None of these

Answer

Correct option: A.
${x^2} + 1$
a
(a) $\frac{{dy}}{{dx}} + \frac{{2x}}{{1 + {x^2}}}y = \frac{{{x^2} - 1}}{{{x^2} + 1}}$

$I.F.$ $ = {e^{\int {\frac{{2x}}{{1 + {x^2}}}dx} }} = {e^{\log (1 + {x^2})}}$$ = 1 + {x^2}$.
 

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