SOLUTION: If x-y=4 and xy=21 find x^3-y^3

SOLUTION: If x-y=4 and xy=21 find x^3-y^3

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Question 1037399: If x-y=4 and xy=21 find x^3-y^3
Answer by ikleyn(52781) (Show Source): You can put this solution on YOUR website!
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If x-y=4 and xy=21 find x^3-y^3
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 =    (which is classic identity)

=    (now plug-in the given data)

= 4*(4^2 +3*21) = 4*(16+63) = 4*79 = 316.

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