SOLUTION: Please help me solve this question. integrate the following indefinite integrals: 4x-3 ---------- dx (x+1)^2

Algebra ->  Trigonometry-basics -> SOLUTION: Please help me solve this question. integrate the following indefinite integrals: 4x-3 ---------- dx (x+1)^2      Log On


   



Question 469479: Please help me solve this question.
integrate the following indefinite integrals:
4x-3
---------- dx
(x+1)^2

Found 2 solutions by Edwin McCravy, Tatiana_Stebko:
Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
You must use partial fractions:

  4x-3         A        B
 ------- =  ------- + ----- 
 (x+1)²      (x+1)²    x+1

    4x-3 = A + B(x+1)

This must be an identity for all x

   Let x = -1

 4(-1)-3 = A + B(-1+1)

    -4-3 = A + 0

       A = -7

    4x-3 = A + B(x+1) becomes

    4x-3 = -7 + B(x+1)

   Let x = 0

4(0) - 3 = -7 + B(0+1)

      -3 = -7 + B

       4 = B

So now

  4x-3         A        B
 ------- =  ------- + ----- 
 (x+1)²      (x+1)²    x+1

becomes

  4x-3         -7       4
 ------- =  ------- + ----- 
 (x+1)²      (x+1)²    x+1


So now the problem becomes the sum of two integrals


int%28%284x-3%29%2F%28x%2B1%29%5E2%2Cdx%29=int%28%28-7%29%2F%28x%2B1%29%5E2%2Cdx%29+int%284%2F%28x%2B1%29%2Cdx%29%29 = -7int%28%28x%2B1%29%5E%28-2%29%2Cdx%29+4int%28dx%2F%28x%2B1%29%29



Now you can finish it, right? If not post again asking how.
The fist integral is simply un and the second is 
a natural log.

Edwin

Answer by Tatiana_Stebko(1539) About Me  (Show Source):
You can put this solution on YOUR website!
int%28%28%284x-3%29%2F%28x%2B1%29%5E2%29dx%29%29
Substitute x%2B1=t, x=t-1, dx=dt
int%28%28%284%28t-1%29-3%29%2Ft%5E2%29dt%29=int%28%28%284t-4-3%29%2Ft%5E2%29dt%29=int%28%28%284t-7%29%2Ft%5E2%29dt%29=int%28%28%284t%2Ft%5E2%29-7%2Ft%5E2%29dt%29=int%28%284t%2Ft%5E2%29dt%29-int%28%287%2Ft%5E2%29dt%29=4int%28%281%2Ft%29dt%29-7int%28t%5E%28-2%29dt%29=4ln%28abs%28t%29%29-7%28t%5E%28-1%29%2F%28-1%29%29%2BC=4ln%28abs%28t%29%29%2B7%2Ft%2BC=
Substitute t=x%2B1
=4ln%28abs%28x%2B1%29%29%2B7%2F%28x%2B1%29%2BC