Question

Evaluate ∫ xe2x dx. 1 2 3x A./xe +C 6 B.1/xe2x-1/ xe2x+C 22 C.1/xe2x-1/ e2x+C 24 1 2 1 4x D./x-/e +C 28

Answer 1

The answer is (1/2)xe^(2x) - (1/4)e^(2x) + C

Solution:
Since our given integrand is the product of the functions x and e^(2x), we can use the formula for integration by parts by choosing
     u = x
     dv/dx = e^(2x)

By differentiating u, we get
     du/dx= 1
By integrating dv/dx= e^(2x), we have
     v =∫e^(2x) dx = (1/2)e^(2x)

Then we substitute these values to the integration by parts formula:
     ∫ u(dv/dx) dx = uv −∫ v(du/dx) dx 
     ∫ x e^(2x) dx = (x) (1/2)e^(2x) - ∫ ((1/2) e^(2x)) (1) dx
                          = (1/2)xe^(2x) - (1/2)∫[e^(2x)] dx
                          = (1/2)xe^(2x) - (1/2) (1/2)e^(2x) + C
where c is the constant of integration.

Therefore, 
     ∫ x e^(2x) dx = (1/2)xe^(2x) - (1/4)e^(2x) + C