teenandtoddlermom
need help
(x^3+y^2)(x^3-y^2)
can someone help me figure this out and explain?
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anonymous
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you have to do four multiplications
teenandtoddlermom
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I need to multiply
anonymous
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\[x^3\times x^3\] is the first one
teenandtoddlermom
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x^6? do I add the exponents?
anonymous
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then \(x^3\times (-y^2)\)
anonymous
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yes
anonymous
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then \(x^3\times y^2\)
anonymous
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and finally \(y^2\times (-y)^2\)
anonymous
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you will notice that middle terms add up to zero, so you are only left with
\[x^6-y^4\]
anonymous
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yes
anonymous
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it is always true that \((a+b)(a-b)=a^2-b^2\)
teenandtoddlermom
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see, all I need is confidence and your great guidings! :) I might make it after all. LOL
jim_thompson5910
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you can also use a table to help you multiply
|dw:1362367881354:dw|
teenandtoddlermom
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Hi Jim. thank you, that helps as well. :)
jim_thompson5910
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each cell is the result of multiplying the corresponding row and column headers
so the upper left cell is the result of multiplying the two x^3 terms
the upper right cell is the result of multiplying x^3 and y^2
etc etc
giving you this
|dw:1362367968379:dw|
jim_thompson5910
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then you add up all the terms and combine like terms if you can to get x^6 - y^4 (the x^3y^2 terms will cancel as you got before)
teenandtoddlermom
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great explanation. I need all the tips I can get. thank you! :)
jim_thompson5910
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you're welcome