document.write( "Question 715626: Find the value of 27(x^3) - 108(x^2)y + 144xy^2 - 64(y^3) , when x = 2, y = (-1) \n" ); document.write( "

Algebra.Com's Answer #439544 by KMST(5328) $\"\"$ $\"About$

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$\"27x%5E3+-+108x%5E2y+%2B+144xy%5E2+-+64y%5E3=%283x-4y%29%5E3\"$
\n" ); document.write( "When $\"x=2\"$ and $\"y=-1\"$
\n" ); document.write( " $\"3x-4y=3%2A2-4%28-1%29=6%2B4=10\"$ and $\"%283x-4y%29%5E3=10%5E3=highlight%281000%29\"$
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\n" ); document.write( "If you realize that $\"27x%5E3=%283x%29%5E3\"$ is a perfect cube,
\n" ); document.write( "and/or realize that $\"-64y%5E3=%28-4y%29%5E3\"$ is a perfect cube,
\n" ); document.write( "you have to suspect that $\"27x%5E3+-+108x%5E2y+%2B+144xy%5E2+-+64y%5E3\"$ might be
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