Hi. I worked this question many times.
28-2-20
(int)2 sqrt(1 - (e^(-x))) ((e^(-x)) dx)
General Power Formula:
u^(n+1) / (n + 1) = u^n du
Attempt:
u = (1 - e^(-x))
n = 1/2
du = -e^(-x) * - 1
du = e^(-x)
= (1 - e^(-x))^(1/2) / (3/2)
Pretty sure this is the wrong direction though, as the answer according to the Ti-89 is much more elaborate