SOLUTION: I need help with this problem please factor each expression y2-81

Question 88224: I need help with this problem please
factor each expression
y2-81
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
Start with the given expression

Let and . So we get this:

Since , A can be solved for:
Take the square root of both sides

Since , B can be solved for:
Take the square root of both sides

Since we have a difference of squares, we can factor it like this:

Now replace A and B
Plug in and

So the expression

factors to

Notice that if you foil the factored expression, you get the original expression. This verifies our answer.
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