Using the substitution u=sqrtxu=x, how do you integrate int e^sqrtx/sqrtxexx from [1,4]?

1 Answer
Jan 11, 2017

int_1^4 e^sqrt(x)/sqrt(x) dx = 2e(e-1)41exxdx=2e(e1)

Explanation:

If we substitute:

u = sqrt(x)u=x

we have:

du = (dx) / (2sqrt(x))du=dx2x

and of course:

x=1 => u = 1x=1u=1
x=4 => u=2x=4u=2

So:

int_1^4 e^sqrt(x)/sqrt(x) dx = 2 int_1^2 e^udu = [e^u]_1^2 = 2(e^2-e)= 2e(e-1)41exxdx=221eudu=[eu]21=2(e2e)=2e(e1)