SOLUTION: Add: x/x^2 - 81 + 9/81 - x^2

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Question 156272: Add:
x/x^2 - 81 + 9/81 - x^2
Answer by orca(409) About Me  (Show Source):
You can put this solution on YOUR website!
Note that:
81+-+x%5E2=-%28x%5E2-81%29
So
x%2F%28x%5E2-81%29%2B9%2F%2881-x%5E2%29
=x%2F%28x%5E2-81%29%2B9%2F%28-%28x%5E2-81%29%29
=x%2F%28x%5E2-81%29-9%2F%28x%5E2-81%29
=%28x-9%29%2F%28x%5E2-81%29
=%28x-9%29%2F%28x%5E2-9%5E2%29
=%28x-9%29%2F%28%28x%2B9%29%28x-9%29%29 (factor x^2-9^2 into (x+9)(x-9))
=cross%28%28x-9%29%29%2F%28%28x%2B9%29cross%28%28x-9%29%29%29
=1%2F%28x%2B9%29