Question

A+b+c=11 ab+bc+ca=20 find the value of a^3+b^3+c^3

Answer 1

a³+b³+c³
= (a+b+c)(a²+b²+c²-ab-bc-ca)
= (a+b+c) {(a+b+c)²-3(ab+bc+ca)]. [(a+b+c)²=a²+b²+c²+2(ab+bc+ca)]
= 11 {(11)² -3*20}. [Setting the given values]
=11 (121-60) =11*61 = 671

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