SOLUTION: 6x^2+7xy-3y^2-8y+10y+c can be factorized, Q: what is c?

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Question 1164354: 6x^2+7xy-3y^2-8y+10y+c can be factorized, Q: what is c?
Answer by greenestamps(13203) About Me  (Show Source):
You can put this solution on YOUR website!


It is almost certain that you have not shown the expressions correctly.

Specifically, you show two linear y terms and no linear x term.

It would seem advantageous to you to check your post before you submit it....

Nevertheless, I will go through this with you, because it is an interesting problem.

I have changed the "-8y" term to "-8x"....

6x%5E2%2B7xy-3y%5E2-8x%2B10y%2Bc+=+%28Ax%2BBy%2BC%29%28Dx%2BEy%2BF%29

We know the coefficient of the x^2 term is AD=6; we need to find the constant term CF.

Since AD is 6, we can have A and D be either 6 and 1, or 3 and 2. It is more likely that they are 3 and 2; so let's try that and see if we can reach an answer.



Equating coefficients with the given expression, we have

2B%2B3E+=+7
BE+=+-3
2C%2B3F+=+-8
BF%2BCE+=+10

Without going through the details (they aren't hard), the first two equations give us B = -1 and E = 3.

Then, knowing B = -1 and E = 3, the last two equations give us

2C%2B3F+=+-8
3C-F+=+10

Again without the details, those two equations give us C = 2 and F = -4.

And that gives us our answer: CF = -8.

The result is easily confirmed by doing the multiplication: