HP50G integration

jhox08

can someone help me understand our to do substitution when I try to integrate, for example I use the equation writer and INTVX to try to integrate -1/2*e^(-x/2)*sin(5*x), the calculator goes into approx mode and returns -INT[.5sin(5xt)/e^(xt/2),xt,x], I've tried reading the manual but that doesn't help me, can someone tell me what steps I need to do next to this to integrate properly......thanks