Question 462091
Factor when possible: 
x^2+10xy+9y^2 
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Think of 2 numbers whose product is 9
and whose sum is 10.
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The numbers are 9 and 1
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Rewrite the problem substituting 9xy+xy for 10xy
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x^2+9xy+xy+9y^2
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Factor the 1st 2 and the last 2 terms separately:
= (x(x+9y)) + y(x+9y)
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Factor again:
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= (x+9y)(x+y)
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Cheers,
Stan H.
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