How do you use substitution to integrate x/sqrt(x+4) dxxx+4dx?

2 Answers
Jul 29, 2015

The process is outlined below.

Explanation:

We are to evaluate, int x/(x + 4)^(1/2)*dxx(x+4)12dx.

We shall accomplish this by substitution.

Let, (x + 4) = t(x+4)=t
implies dx = dtdx=dt (By simple differentiation).

Thus, the integral becomes,

int x/(x +4)^(1/2)*dx = int (t - 4)/t^(1/2)*dtx(x+4)12dx=t4t12dt

= int t^(1/2)*dt - int 4t^(-1/2)*dt=t12dt4t12dt

=2/3 t^(3/2) - 8t^(1/2) + C=23t328t12+C, where CC is the integration constant.

In terms of xx, the integral may be now written as,

int x/(x + 4)^(1/2)*dx =2/3 (x + 4)^(3/2) - 8(x + 4)^(1/2) + Cx(x+4)12dx=23(x+4)328(x+4)12+C.

Aug 15, 2017

int x/(sqrt(x+4)) "d"x = 2/3 (x+4)sqrt(x+4) - 8 sqrt(x+4) + Cxx+4dx=23(x+4)x+48x+4+C

Explanation:

int x/(sqrt(x+4)) "d"x = int (x+4-4)/(sqrt(x+4)) "d"xxx+4dx=x+44x+4dx,
int x/(sqrt(x+4)) "d"x = int (x+4)/((x+4)^(1/2))-4/((x+4)^(1/2)) "d"xxx+4dx=x+4(x+4)124(x+4)12dx,
int x/(sqrt(x+4)) "d"x = int (x+4)^(1/2)-4(x+4)^(-1/2) "d"xxx+4dx=(x+4)124(x+4)12dx,
int x/(sqrt(x+4)) "d"x = 2/3(x+4)^(3/2)-8(x+4)^(1/2) + Cxx+4dx=23(x+4)328(x+4)12+C