SOLUTION: Multipy the following polynomial as indicated (7y^2+x)(y^2-2x)

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Question 569735: Multipy the following polynomial as indicated (7y^2+x)(y^2-2x)
Answer by AnlytcPhil(1806) About Me  (Show Source):
You can put this solution on YOUR website!
Remember the word FOIL. F for FIRSTS, O for OUTERS, I for INNERS, 
and L for LASTS.

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The FIRSTS are the 7y² and the 

(7y²+x)(-2x)

That's because the 7y² comes FIRST in the (7y²+x)
and the  comes FIRST in the (-2x)

So we multiply them together

7y²·y² = 7y4

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The OUTERS are the 7y² and the -2x

(7y²+x)(y²-2x)

That's because the 7y² and the -2x are on the OUTSIDE
(That is they are the farthest OUT from each other)

So we multiply them together

7y²·-2x = -14xy²

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The INNERS are the +x and the 

(7z²+x)(-2x)

That's because the +x and the  are on the INSIDE
(That is they are in the middle)

So we multiply them together

+x·y² = +xy²

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The LASTS are the +x and the -2x

(7y²+x)(y²-2x)

That's because the +x comes LAST in the (7y²+x)
and the -2x comes LAST in the (y²-2x)

So we multiply them together

+x·-2x = -2x²

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Write down the four terms from above for FIRSTS, OUTERS, INNERS, and LASTS:

7y4-14xy²+xy²-2x²

The two middle terms are like terms, so they will combine as -13xy²

Answer: 7y4-13xy²-2x² 

Edwin