What is int_0^4 x/(x^2+9)^(1/2) dx∫40x(x2+9)12dx ?
1 Answer
Feb 15, 2017
Explanation:
Note that:
d/(dx) (x^2 + 9) = 2xddx(x2+9)=2x
So:
int_0^4 x/(x^2+9)^(1/2) dx = int_0^4 1/2(d/(dx)(x^2+9))(x^2+9)^(-1/2) dx∫40x(x2+9)12dx=∫4012(ddx(x2+9))(x2+9)−12dx
color(white)(int_0^4 x/(x^2+9)^(1/2) dx) = [(x^2+9)^(1/2)]_0^4∫40x(x2+9)12dx=[(x2+9)12]40
color(white)(int_0^4 x/(x^2+9)^(1/2) dx) = (color(blue)(4)^2+9)^(1/2)-(color(blue)(0)^2+9)^(1/2)∫40x(x2+9)12dx=(42+9)12−(02+9)12
color(white)(int_0^4 x/(x^2+9)^(1/2) dx) = (16+9)^(1/2)-(9)^(1/2)∫40x(x2+9)12dx=(16+9)12−(9)12
color(white)(int_0^4 x/(x^2+9)^(1/2) dx) = 5-3∫40x(x2+9)12dx=5−3
color(white)(int_0^4 x/(x^2+9)^(1/2) dx) = 2∫40x(x2+9)12dx=2