dxdy+2y=f(x) is a linear differential equation.
Integrating Factor =e∫2dx=e2x
Solution of the above equation is
y.e2x=∫f(x).e2xdx+C
y(x)=e−2x∫0xf(x).e2xdx+Ce−2x
y(0)=0⇒C=0
⇒y(x)=e−2x∫0xf(x).e2xdx
∴y(23)=e−3[∫01e2xdx+∫13/20.dx]=2e−3[e2−1]=2e3e2−1