The particular solution of the differential equation $e^x\sqrt{1-y^2}dx +\frac{y}{x} dy = 0$, given that $y = 1$, when $x = 0$, is:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → $\sqrt{1-y^2}=(x-1)e^x +1$
Given differential equation
$e^x\sqrt{1-y^2}\,dx+\frac{y}{x}\,dy=0$
Rearrange
$\frac{y}{x}\,dy=-e^x\sqrt{1-y^2}\,dx$
Separate variables
$\frac{y}{\sqrt{1-y^2}}\,dy=-xe^x\,dx$
Integrate
$\int\frac{y}{\sqrt{1-y^2}}\,dy=-\int xe^x\,dx$
$-\sqrt{1-y^2}=-(x-1)e^x+C$
$\sqrt{1-y^2}=(x-1)e^x+C$
Given $y=1$ at $x=0$
$\sqrt{1-1}=(-1)e^0+C$
$0=-1+C$
$C=1$
Hence particular solution
$\sqrt{1-y^2}=(x-1)e^x+1$
The correct answer is $\sqrt{1-y^2}=(x-1)e^x+1$.