find acube-bcube

Asked by  | 30th Aug, 2012, 05:41: PM

Expert Answer:

a^3 - b^3 = (a-b)(a^2 + ab + b^2)
               = 6(a^2 + b^2 + 20)
 
(a-b)^2 = a^2 + b^2 - 2ab
36 = a^2 + b^2 - 40
a^2 + b^2 = 76
 
Therefore,
a^3 - b^3 = 6(76 + 20) = 6 x 96 = 576

Answered by  | 30th Aug, 2012, 05:53: PM

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