WBJEE 2020 Math Solved Paper

y = ex (A cos x + B sin x)
Differentiating w.r.t. x:-
y' = y + ex (-Asin x + B cos x)
Differentiating w.r.t. x once again:-
y" = y' + (y' – y) + ex (–A cos x – B sin x)
= 2y' – y – y ⇒ y" – 2y' + 2y = 0