## Mom needs help teaching factoring

Quadratic equations and inequalities, variation equations, function notation, systems of equations, etc.
kmillin
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Joined: Thu Feb 06, 2014 5:36 am
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### Mom needs help teaching factoring

My daughter has a problem that I cannot figure out how the teacher's book came up with the answer. They did not provide the intermediate step and there are several like this. If I can see how one is worked, I can figure out the other ones.. Here is the problem....Directions: Factor each polynomial completely.

49x^2 + 28square root of 3 + 12

The answer given is (7x + 2square root of 3)^2

I can get from the answer to the problem but what comes in between!!

Thanks for your help!

Kathy

maggiemagnet
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Joined: Mon Dec 08, 2008 12:32 am
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### Re: Mom needs help teaching factoring

Directions: Factor each polynomial completely.

49x^2 + 28square root of 3 + 12

The answer given is (7x + 2square root of 3)^2
But that doesn't work: (7x + 2sqrt[3])^2 = (7x + 2sqrt[3])(7x + 2sqrt[3]) = (7x)(7x) + (7x)(2sqrt[3]) + (2sqrt[3])(7x) + (2sqrt[3])(2sqrt[3]) = 49x^2 + 28sqrt[3]x + 4*3. You'd need the middle term to have an x in it for the factoring to work that way.

kmillin
Posts: 2
Joined: Thu Feb 06, 2014 5:36 am
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### Re: Mom needs help teaching factoring

Could it be that the teacher's book is (gasp!)....wrong?? There are 4 problems with this format (x^2 + #sqrt# + # OR #x^2 + #sqrt# + #). It really has me baffled.....I keep wondering if we need to somehow deal with the last two factors since they are constants before we factor out the whole problem (but then I go back to....where does the x go? I understand your point about the 28sqrt3 x!

Thanks!