SOLUTION: factor 8x^3y^5+16y^3x^5-40x^4y^4

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Question 115468: factor
8x^3y^5+16y^3x^5-40x^4y^4

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
8x%5E3y%5E5%2B16y%5E3x%5E5-40x%5E4y%5E4 Start with the given expression


8x%5E3y%5E3%28y%5E2%2B2x%5E2-5xy%29 Factor out the GCF 8x%5E3y%5E3


8x%5E3y%5E3%28y%5E2-5xy%2B2x%5E2%29 Sort the terms

Looking at y%5E2-5xy%2B2x%5E2 we can see that the first term is y%5E2 and the last term is 2x%5E2 where the coefficients are 1 and 2 respectively.

Now multiply the first coefficient 1 and the last coefficient 2 to get 2. Now what two numbers multiply to 2 and add to the middle coefficient -5? Let's list all of the factors of 2:



Factors of 2:
1,2

-1,-2 ...List the negative factors as well. This will allow us to find all possible combinations

These factors pair up and multiply to 2
1*2
(-1)*(-2)

note: remember two negative numbers multiplied together make a positive number


Now which of these pairs add to -5? Lets make a table of all of the pairs of factors we multiplied and see which two numbers add to -5

First NumberSecond NumberSum
121+2=3
-1-2-1+(-2)=-3

None of these pairs of factors add to -5. So the inner expression cannot be factored


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Answer:
So that means 8x%5E3y%5E5%2B16y%5E3x%5E5-40x%5E4y%5E4 factors to 8x%5E3y%5E3%28y%5E2%2B2x%5E2-5xy%29