SOLUTION: Find the value of 27(x^3) - 108(x^2)y + 144xy^2 - 64(y^3) , when x = 2, y = (-1)

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Question 715626: Find the value of 27(x^3) - 108(x^2)y + 144xy^2 - 64(y^3) , when x = 2, y = (-1)
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
27x%5E3+-+108x%5E2y+%2B+144xy%5E2+-+64y%5E3=%283x-4y%29%5E3
When x=2 and y=-1
3x-4y=3%2A2-4%28-1%29=6%2B4=10 and %283x-4y%29%5E3=10%5E3=highlight%281000%29

If you realize that 27x%5E3=%283x%29%5E3 is a perfect cube,
and/or realize that -64y%5E3=%28-4y%29%5E3 is a perfect cube,
you have to suspect that 27x%5E3+-+108x%5E2y+%2B+144xy%5E2+-+64y%5E3 might be