Let $e^{αy} + e^{βy} + γx^2 +δ\log |x| + C = 0$, where $C∈R$ be a particular solution of the differential equation $x(e^{2y}-1)dy+(x^2 - 1)e^y\, dx = 0$ and passes through the point (1, 1). The value of $(α+β+γ+δ-C)$ is |
$e-1$ $e^2-1$ $e+\frac{1}{e}$ $\frac{1}{e}$ |
$e+\frac{1}{e}$ |
The correct answer is Option (3) → $e+\frac{1}{e}$ Given differential equation $x(e^{2y}-1)\,dy+(x^2-1)e^y\,dx=0$ Divide both sides by $e^y$ $x(e^y-e^{-y})\,dy+(x^2-1)\,dx=0$ Separate variables $x(e^y-e^{-y})\,dy=-(x^2-1)\,dx$ Divide by $x$ $(e^y-e^{-y})\,dy=-\left(x-\frac{1}{x}\right)dx$ Integrate both sides $\int(e^y-e^{-y})\,dy=-\int\left(x-\frac{1}{x}\right)dx$ $e^y+e^{-y}=-\left(\frac{x^2}{2}-\log|x|\right)+C$ $e^y+e^{-y}+\frac{x^2}{2}-\log|x|+C=0$ Compare with $e^{\alpha y}+e^{\beta y}+\gamma x^2+\delta\log|x|+C=0$ $\alpha=1,\;\beta=-1,\;\gamma=\frac12,\;\delta=-1$ Use point $(1,1)$ $e+e^{-1}+\frac12-\log1+C=0$ $C=-(e+e^{-1}+\frac12)$ Compute $\alpha+\beta+\gamma+\delta-C=1-1+\frac12-1-[-(e+e^{-1}+\frac12)]$ $=-\frac12+e+e^{-1}+\frac12$ $=e+e^{-1}$ The value of $\alpha+\beta+\gamma+\delta-C$ is $e+\frac{1}{e}$. |