SOLUTION: Factor the trinomial completely x^2y^2-6xy+9

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Question 191475: Factor the trinomial completely
x^2y^2-6xy+9

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

Looking at x%5E2y%5E2-6xy%2B9 we can see that the first term is x%5E2y%5E2 and the last term is 9 where the coefficients are 1 and 9 respectively.

Now multiply the first coefficient 1 and the last coefficient 9 to get 9. Now what two numbers multiply to 9 and add to the middle coefficient -6? Let's list all of the factors of 9:



Factors of 9:
1,3

-1,-3 ...List the negative factors as well. This will allow us to find all possible combinations

These factors pair up and multiply to 9
1*9
3*3
(-1)*(-9)
(-3)*(-3)

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


Now which of these pairs add to -6? Lets make a table of all of the pairs of factors we multiplied and see which two numbers add to -6

First NumberSecond NumberSum
191+9=10
333+3=6
-1-9-1+(-9)=-10
-3-3-3+(-3)=-6



From this list we can see that -3 and -3 add up to -6 and multiply to 9


Now looking at the expression x%5E2y%5E2-6xy%2B9, replace -6xy with -3xy-3xy (notice -3xy%2B-3xy adds up to -6xy. So it is equivalent to -6xy)

x%5E2y%5E2%2Bhighlight%28-3xy-3xy%29%2B9


Now let's factor x%5E2y%5E2-3xy-3xy%2B9 by grouping:


%28x%5E2y%5E2-3xy%29%2B%28-3xy%2B9%29 Group like terms


xy%28xy-3%29-3%28xy-3%29 Factor out the GCF of xy out of the first group. Factor out the GCF of -3 out of the second group


%28xy-3%29%28xy-3%29 Since we have a common term of xy-3, we can combine like terms

So x%5E2y%5E2-3xy-3xy%2B9 factors to %28xy-3%29%28xy-3%29


So this also means that x%5E2y%5E2-6xy%2B9 factors to %28xy-3%29%28xy-3%29 (since x%5E2y%5E2-6xy%2B9 is equivalent to x%5E2y%5E2-3xy-3xy%2B9)


note: %28xy-3%29%28xy-3%29 is equivalent to %28xy-3%29%5E2 since the term xy-3 occurs twice. So x%5E2y%5E2-6xy%2B9 also factors to %28xy-3%29%5E2



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Answer:
So x%5E2y%5E2-6xy%2B9 factors to %28xy-3%29%5E2