InterviewSolution
| 1. |
Show that y = ex (A cosx + B sinx) is a solution of the differential equation \(\frac{d^2y}{dx^2}-2\frac{dy}{dx} + 2y = 0\) |
|
Answer» The differential equation is \(\frac{d^2y}{dx^2}-2\frac{dy}{dx} + 2y = 0\) and the function to be proven as the solution is y = ex(A cosx + B sinx), we need to find the value of \(\frac{dy}{dx}.\) \(\frac{dy}{dx}=\) ex(A cos x + B sin x) + ex(–A sin x + B cos x) \(\frac{d^2y}{dx^2}=\) ex(A cos x + B sin x) + ex(–A sin x + B cos x) + ex(–A sin x + B cos x) + ex(–A cos x – B sin x) = 2ex(–A sin x + B cos x) Putting the values in equation, 2ex(–A sin x + B cos x) – 2ex(A cos x + B sin x) – 2ex(–A sin x + B cos x) + 2ex(A cos x + B sin x) = 0 0 = 0 As, L.H.S = R.H.S. the equation is satisfied, hence this function is the solution of the differential equation. |
|