Consider the differential equation $xdy - (y+2x^3)dx$. Then which of the following are TRUE? (A) It is a homogeneous differential equation. Choose the correct answer from the options given below: |
(A), (B) and (C) only (B), (C) and (D) only (B) and (D) only (A), (C) and (D) only |
(B) and (D) only |
The correct answer is Option (3) → (B) and (D) only $\text{Given: }x\frac{dy}{dx}=y+2x^{3}\;\Rightarrow\;\frac{dy}{dx}-\frac{1}{x}y=2x^{2}$ $\text{(A) Not homogeneous (term }2x^{2}\text{ prevents dependence only on }y/x)$ $\text{(B) Order }=1,\ \text{degree }=1\ \Rightarrow\ \text{product }=1\ (\text{True})$ $\text{(C) Integrating factor }=e^{\int(-1/x)\,dx}=e^{-\ln x}=\frac{1}{x}\neq x\ (\text{False})$ $\text{(D) With IF } \frac{1}{x}:\ \frac{d}{dx}\!\left(\frac{y}{x}\right)=2x\ \Rightarrow\ \frac{y}{x}=x^{2}+C$ $\Rightarrow\ y=x^{3}+Cx\ (\text{True})$ True statements: (B) and (D) |