Divide through by to get

The integrating factor is (Verify)

Thus, the DE becomes

Can you take it from here??

Separating the variables, you have(1 + x^2) dy/dx = y where y(0) = 1

Can you take it from here?

Divide through by to gett* dy/dt - y = t^3 sin t where y(Pi) = 0

The integrating factor is

Thus, the DE becomes

Can you take it from here?

Does this make sense?