SOLUTION: i am to do this math problem and are having a rough time of it and i would like your assitance. the problem is to solve using addition or subtraction. I set it up as addition but

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: i am to do this math problem and are having a rough time of it and i would like your assitance. the problem is to solve using addition or subtraction. I set it up as addition but       Log On


   

Question 972471: i am to do this math problem and are having a rough time of it and i would like your assitance.
the problem is to solve using addition or subtraction. I set it up as addition but is that right?
x^2-3x-9/x-9 + x^2-7x+27/9-x
now I understand that the denominators need to be the same but I'm confused as to how this is done.
also, do I add both numerators together or should i subtract. I tried to work the problem already but I'm so lost. i do know the answer key has an answer of 4. I just can't find that answer.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
%28x%5E2-3x-9%29%2F%28x-9%29 + %28x%5E2-7x%2B27%29%2F%289-x%29
right now the denominators are not the same but we can make them the same
Factor out -1 from the 2nd denominator
%28x%5E2-3x-9%29%2F%28x-9%29 + %28x%5E2-7x%2B27%29%2F%28-1%28x-9%29%29
dividing -1 into the numerator, changes the sign so we have
%28x%5E2-3x-9%29%2F%28x-9%29 - %28x%5E2-7x%2B27%29%2F%28x-9%29
now we can write it:
%28%28x%5E2-3x-9%29-%28x%5E2-7x%2B27%29%29%2F%28x-9%29
removing the brackets changes the signs after the minus
%28x%5E2-3x-9-x%5E2%2B7x-27%29%2F%28x-9%29
combine like terms
%28x%5E2-x%5E2-3x%2B7x-9-27%29%2F%28x-9%29
now we have
%284x-36%29%2F%28x-9%29
factor 4 out in the numerator, (x-9) cancels
%284%28x-9%29%29%2F%28x-9%29 = 4