Tuesday, December 25, 2018

int (1/(2x+5) - 1/(2x-5)) dx Find the indefinite integral

int (1/(2x+5)-1/(2x-5))dx
To solve, express it as difference of two integrals.
= int 1/(2x+5)dx - int 1/(2x-5)dx
Then, apply substitution method.
u=2x+5

du=2dx
1/2du=dx

w=2x-5

dw=2dx
1/2dw=dx

Expressing the two integrals in terms of u and w, it becomes
= int 1/u*1/2 du - int 1/w*1/2dw
=1/2int1/u du- 1/2 int1/w dw
To take the integral of these, apply the formula int 1/x dx = ln|x|+C .
= 1/2 ln|u| - 1/2 ln|w|+C
And, substitute back u= 2x+5 and w=2x-5.
=1/2ln|2x+5|-1/2ln|2x-5|+C
Therefore,  int (1/(2x+5)-1/(2x-5))dx=1/2ln|2x+5|-1/2ln|2x-5|+C .

No comments:

Post a Comment

Why is the fact that the Americans are helping the Russians important?

In the late author Tom Clancy’s first novel, The Hunt for Red October, the assistance rendered to the Russians by the United States is impor...