SOLUTION: Factor completely 81s^2+64-144s

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Question 442441: Factor completely 81s^2+64-144s
Answer by swincher4391(1107) About Me  (Show Source):
You can put this solution on YOUR website!
Recognize in your problem 81s^2-144s+64 that 81 and 64 are perfect squares.
%289s%29%5E2+=+81s%5E2 and %288%29%5E2+=+64
Also recognize that the middle term is negative, while the last term is positive. In order to achieve a negative sum and positive product, both constants have to be negative... for instance -3 * -3 = 9, and -3 + -3 = -6.
Given this information, we have all we need to solve this.
Remember 81s^2 = (9s)^2 , so our first term in our factor will be 9s.
Similarly with 64 = 8^2.
So our factorization will be %289s-8%29%5E2
Let's FOIL to make sure.
%289s-8%29%5E2+=+%289s-8%29%289s-8%29+=+81s%5E2+-72s+-72s+%2B+64+=+81s%5E2+-144s+%2B164
Check.
Hope this helped!