Problem with threee differential equations

Can someone help me with these three equatons. They have to solve with matlab code.

Here are :

1.

y'' - y = 0

y(0)=0

y(1)=1

2.

y''-y=-4(sin^3)x + 9sinx

y(0) = y(2*pi)

3.

Ut=Uxx + U + 2sin2xsinx

U = U(x,t) where x is (0;pi/2) and t >0

Thnak you in advance!