Variation of Parameters
3. y" - 2y' + y = x^2 e^x
4. The Method of Variation of Parameters can be used to find the general solution of the following differential equation
(D - 1/2)^2 y = x^-2e^x/2
The solution has the form: y = v_1(x) middot e^x/2 + v2(x) middot xe^x/2
where v1 (x) and v2 (x) are functions. Calculate the function v1 (x)