Differential Equations Question 181

Question: The solution of the differential equation $ \frac{dy}{dx}+\frac{y}{x}=x^{2} $ is

Options:

A) $ 4xy=x^{4}+c $

B) $ xy=x^{4}+c $

C) $ \frac{1}{4}xy=x^{4}+c $

D) $ xy=4x^{4}+c $

Show Answer

Answer:

Correct Answer: A

Solution:

The given equation $ \frac{dy}{dx}+\frac{y}{x}=x^{2} $ is of the form $ \frac{dy}{dx}+Py=Q $ . So, I.F.= $ {e^{\int _{{}}^{{}}{\frac{1}{x}dx}}}={e^{\log x}}=x $

Hence required solution $ xy=\int _{{}}^{{}}{x.x^{2}dx+c} $

Therefore $ xy=\frac{x^{4}}{4}+c $

Therefore $ 4xy=x^{4}+c $ .