MCQ
The Integrating Factor of the differential equation $\text{x}\frac{\text{dy}}{\text{dx}}-\text{y}=2\text{x}^2\ \text{is}$
  • A
    $\text{e}^{-\text{x}}$
  • B
    $\text{e}^{-\text{y}}$
  • $\frac{1}{\text{x}}$
  • D
    $\text{x}$

Answer

Correct option: C.
$\frac{1}{\text{x}}$
The given differential equation is:
$\text{x}\frac{\text{dy}}{\text{dx}}-\text{y}=2\text{x}^2$
$\Rightarrow\frac{\text{dy}}{\text{dx}}-\frac{\text{y}}{\text{x}}=2\text{x}$
This is a linear differential equation of the form:
$\frac{\text{dy}}{\text{dx}}+\text{py}=\text{Q}​​\ (\text{where p}=-\frac{1}{\text{x}}\ \text{and}\ \text{Q}=2\text{x})$
The integrating factor (I.F) is given by the relation,
$​​\text{e}^{\int​​\text{pdx}}$
$\therefore\text{I.F}=\text{e}^{\int-\frac{1}{\text{x}}\text{dx}}=\text{e}^{-\log\text{x}}=\text{e}^{\log(\text{x}^-1)}=\text{x}^{-1}=\frac{1}{\text{x}}$

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