Question

If a +b+c=15 ,a^2+b^2+c^2=83then find the value of a^3+b^3+c^3-3abc

Answer 1

(a+b+c)²=15²
a²+b²+c²+2(ab+bc+ca)=225
83+2(ab+bc+ca)=225
ab+bc+ca=142/2
ab+bc+ca=71
a³+b³+c³-3abc=
we can use the identity