[SOLVED] finding surface area using parametric equations

The question reads

Find the surface area generated by rotating x=e^t -t & y=4e^t for 0 to 1 (this is in terms of t) about the y axis.

So i've managed to get the integral as far as

(e^(t)-t)((e^(2t)+1)^1/2)

i'm just not sure what to do after that i thought about multiplying out the square root but even if i were to do that i can't think of a proper u-sub that could work. So what do you think am i on the right track or is there an easier way that i'm just not seeing.