ShmoopTube

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And here is your shmoop de jour.

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Solve for x: x squared plus 6x plus 8 equals 0

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And here are the potential answers...

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OK. Any time we see equations in this format -- where there's an x squared then and

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x then an integer -- odds are high that they're asking us to factor.

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What 2 numbers can be multiplied to get 8... and can also be added to get 6?

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Well, the factors of 8 are 1 and 8; that won't work...

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...what about 2 and 4? Ding ding ding!

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So... 2 times 4 is 8... and 2 PLUS 4 is 6... so we can just rewrite the factored version as

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The quantity x plus 2 times the quantity x plus 4... equals zero.

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Now if either of these guys is 0, the whole equation is zero because zero times anything...

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is zero. Yeah, it brings everyone else down to its level.

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So if x is negative 2, this part is 0... and if x is negative 4, this part is 0.

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x has to be one of those answers... and OUR answer here is either A or B... which is...

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option D. Done

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