\frac{dx[t]}{dt}=\frac{y[t]}{RC}+ \frac{dy[t]}{dt}

above is the given equation based on Kirchhoff law.

And the question is:

Find the solution of the ODE to obtain y[t] as some integral of x[t].

I had search through google and found a solution here.

y[t]=\int_{-\infty}^{t} e^{-(t-\lambda)/\tau}x'[\lambda] \,d\lambda

But i do not know how to introduced the e^{-(t-\lambda)/\tau}!! Anyone help!! can any1 provide me some solution??