Oppo math wizards! Halp!

"Alex B" (alexb420) 05/21/2014 at 12:32 • Filed to: None

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So, the final exam is coming up in Algebra, and I'm trying to study for it. The teacher gives out practice problems, and this was one of them. I'm stumped.

Edit:

I had my signs wrong. I put (x+6)(x-2) when it really is (x-6)(x+2). Because of that I couldn't cancel out the proper values. Thanks everyone!

mr_gofast > Alex B 05/21/2014 at 12:33

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bob and john > Alex B 05/21/2014 at 12:38

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hmmm. if i remember coreectly, to devide, u can also multiply by the reverse (top on bottom, bottom on top.

also, split the quadratic. then u get (x +3)(x + 5) / (x - 6) (x+2)

so u end up with (x+3)(x-6)(x+2) / (x-6)(x+3)(x+5) (i think)

cancel them out

do this urself, i'm doing it rushed at work, so i cant say if its correct or not

Reigntastic > Alex B 05/21/2014 at 12:38

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I solved it, let me upload a photo.

bob and john > Alex B 05/21/2014 at 12:39

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give me a minute to try and work it out. i'll say this: split the quadtratics. so X^2+8x+15 is going to be (x+3)(x+5) and the other will end up as (x-6)(x+2)

yamahog > Alex B 05/21/2014 at 12:40

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What part(s) are you stumped with? A good number of us are probably capable of giving you the answer, but we won't be there for your final :P

bob and john > bob and john 05/21/2014 at 12:43

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so, now tht u have that, remember that to devide, u can also multiply by the reciprocal. so, x /2 is also equal to x times 1/2

using this, we get (x+3)/(x-6) divided by [(x+3)(x+5)]/[(x-6)(x+2)}


can u figure it out from here?

55Buick, Oversteer Scientist > Alex B 05/21/2014 at 12:43

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remember that when you divide fractions, it's the same as multiplying by the inverse. Once you get that, split up the quadratics out into their expanded forms and then cancel.

Source: took algebra final yesterday

Alex B > Reigntastic 05/21/2014 at 12:43

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Thanks. I had my signs mixed up. I had (x+6)(x-2) instead of (x-6)(x+2).

Alex B > yamahog 05/21/2014 at 12:47

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I had my signs wrong. I had (x+6)(x-2) vs. (x-6)(x+2). That's what was stumping me.

Alex B > 55Buick, Oversteer Scientist 05/21/2014 at 12:50

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I had my signs wrong, it should've been (x-6)(x+2), but I had (x+6)(x-2). Because of that, I couldn't cancel out the needed values. Did you do well on your final?

Reigntastic > Alex B 05/21/2014 at 12:50

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Simplifying quadratic equations is something you should practice before your final, then.

If both values are positive (x+)(x+), because +x+=+

If both values are negative (x+)(x-), because +x-=-

If positive and negative (x-)(x-), because -x-=+

The integers should combine to make the same value as your x value. For example:(x^2+8x+16)=(x+4)^2

4+4=8

Source: used to be a paid math tutor for grades 9-12

davedave1111 > Alex B 05/21/2014 at 13:02

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It's a multiple choice, so you don't even need to solve it. To get from +3 to +15 requires multiplying by +5, and there's only one answer with a +5 in.

Personally, I always focussed on exam technique more than the subject at hand, because exam technique will boost your grades in every subject. It's amazing how often they give you the answer in the question.