SOLUTION: Divide and Simplify y^2-81 over 4y+36 divide by y-9 over 18

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Divide and Simplify y^2-81 over 4y+36 divide by y-9 over 18      Log On


   

Question 228552: Divide and Simplify
y^2-81 over 4y+36 divide by y-9 over 18
Answer by JenniferTutors(83) About Me  (Show Source):
You can put this solution on YOUR website!
Ok for this problem,
%28y%5E2-81%29%2F%284y%2B36%29/%28y-9%29%2F%2818%29
You want to multiply the reciprocal of the second fraction to start solving:
%28y%5E2-81%29%2F%284y%2B36%29x%2818%29%2F%28y-9%29
Now looking at the numerator of the first fraction, you can simplify by doing the foil method (backwards). Here's how that would look:
%28y%2B9%29%28y-9%29%2F%284y%2B36%29x%2818%29%2F%28y-9%29
Next, for the denominator on the first fraction, you can simplify 4y+36, by dividing a four out of it, here's how it would look:
%28y%2B9%29%28y-9%29%2F%284%29%28y%2B9%29x%2818%29%2F%28y-9%29
Now, you can cross out the like terms from both fractions:
1%2Across%28%28y%2B9%29%29cross%28%28y-9%29%29%2F%284%29cross%28%28y%2B9%29%29x%2818%29%2F1cross%28y-9%29
Now, you're left with
18%2F4
To simplify: 2 goes into both numbers easily
9%2F2