Barrons AP Calculus - David Bock

46. (D) We use parts, first letting u = x^2 , dv = e−x dx; then du = 2x dx, v = −e−x and

Now we use parts again, letting u = x, dv = e−x dx; then du = dx, v = −e−x and

Alternatively, we could use the Tic-Tac-Toe Method:

Then