Practicing Success
The solution of the differentiable equation $2x\frac{dy}{dx}+y=14x^3, x>0$, is |
$y=2x^3+cx^{\frac{1}{2}}$ $y=x^3+cx^{\frac{1}{2}}$ $y=2x^3+cx^{-\frac{1}{2}}$ $y=x^3+cx^{-\frac{1}{2}}$ |
$y=2x^3+cx^{-\frac{1}{2}}$ |
$2x\frac{dy}{dx}+y=14x^3$ dividing by leading 2x $⇒\frac{dy}{dx}\underbrace{\frac{1}{2x}}_{p}y=\underbrace{7x^2}_{q}$ Intergrating factor = $e^{\int pdx}=e^{\int\frac{1}{2x}dx}$ $=e^{\frac{1}{2}ln\,x}=e^{ln\sqrt{x}}=\sqrt{x}$ multiplying eqn with integrating factor $\sqrt{x}\frac{dy}{dx}+\frac{1}{2\sqrt{x}}y=7x^{5/2}$ integrating both side w.r.t. x $\int\sqrt{x}\frac{dy}{dx}+\frac{1}{2\sqrt{x}}ydx=7\int x^{5/2}dx$ $=\sqrt{x}y=7\frac{x^{7/2}}{7}×2+c$ $y=2x^3+cx^{-\frac{1}{2}}$ |