Thanks,
So I have KE = PE(gravity) + W(drag). That is, 1/2mV2 = GMm/r + W(drag).
Now W(drag) is the integral of F(drag), which should equal F(drag) * distance, which is 0.276v2, in my case. I got that by multiplying Δx, (100km-35km=65km), by the drag coefficient I calculated at 35km, 4.257 x...