SOLUTION: 3/(x+1) +4/(x-2)=(px+q)/(x+1)(x-2) What is the value of p and q?

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Question 287802: 3/(x+1) +4/(x-2)=(px+q)/(x+1)(x-2)
What is the value of p and q?

Found 4 solutions by mananth, ikleyn, MathTherapy, KMST:
Answer by mananth(16949) About Me  (Show Source):
You can put this solution on YOUR website!
3/(x+1) +4/(x-2)=(px+q)/(x+1)(x-2)
3(x-2)+4(x+1)= (px+q)(x+1)(x-2)/(x+1)(x-2)
3x-6+4x+4 = (px+q)
7x-2 = px+q
q=(7x-2)-px
p=(7x-2)-q /x

Answer by ikleyn(53875) About Me  (Show Source):
You can put this solution on YOUR website!
.
3/(x+1) +4/(x-2)=(px+q)/(x+1)(x-2)
What is the value of p and q?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


        The answer in the post by @mananth is incorrect.
        I came to bring a correct solution.


3/(x+1) +4/(x-2)=(px+q)/(x+1)(x-2)

Multiply both sides by (x+1)*(x-2).
You will get an equivalent equality

3(x-2)+4(x+1)= (px+q)(x+1)(x-2)/(x+1)(x-2)
3x-6+4x+4 = (px+q)
7x-2 = px+q

Hence, p = 7, q = -2.

ANSWER.   p = 7,   q = -2.


At this point, the solution is complete.



Answer by MathTherapy(10839) About Me  (Show Source):
You can put this solution on YOUR website!
3/(x+1)   +4/(x-2)=(px+q)/(x+1)(x-2)   
What is the value of p and q?
*****************************
3%2F%28x+%2B+1%29+%2B+4%2F%28x+-+2%29+=+%28px+%2B+q%29%2F%28x+%2B+1%29%28x+-+2%29   

Let's focus on the LEFT-SIDE of the equation
            
 ---- Multiplying left-side by GCF (x + 1)(x - 2) 
         
           
                        7x - 2 = px + q --- Equating NUMERATORS, since DENOMINATORS are equivalent
                        7x = px          - 2 = q
                   7x%2Fx+=+px%2Fx
                  7cross%28x%29%2Fcross%28x%29+=+p%2Across%28x%29%2Fcross%28x%29____7 = p

Answer by KMST(5377) About Me  (Show Source):
You can put this solution on YOUR website!
If 3%2F%28x%2B1%29%2B4%2F%28x-2%29=%28px%2Bq%29%2F%28x%2B1%29%28x-2%29 must be true for every value of x ,
it will be true for x=0 and for x=1 .

For x=0 :
3%2F%280%2B1%29%2B4%2F%280-2%29=%28px%2Bq%29%2F%280%2B1%29%280-2%29
3%2F1%2B4%2F%28-2%29=%28p%2A0%2Bq%29%2F%281%28-2%29%29
3%2B%28-2%29=q%2F%28-2%29
Multiplying times %28-2%29 we get
3%28-2%29%2B%28-2%29%28-2%29=q-->-6%2B4=q --> highlight%28q=-2%29

For x=1 :
3%2F%281%2B1%29%2B4%2F%281-2%29=%28p%2A1-2%29%2F%281%2B1%29%281-2%29
3%2F2%2B4%2F%28-1%29=%28p-2%29%2F%282%28-1%29%29
3%2F2-4=%28p-2%29%2F%28-2%29
3%2F2-4=%28p-2%29%2F%28-2%29
Multiplying times %28-2%29 we get
%283%2F2%29%28-2%29-4%28-2%29=p-2
-3%2B8=p-2
8-3%2B2=p --> highlight%28p=7%29