Question

If a+b+c=9 a
nd a^2+b^2+c^2=35
, find the value of a3+b3+c3-3abc.

Answer 1

Answer:

(a+b+c)^2 = a^2+b^2+c^2+2(ab+bc+ca)

hence, ab+bc+ca=(81-35)/2=23

(a+b+c)^3 = a^3+b^3+c^3-3abc+3(a+b+c)(ab+bc+ca)

hence, a^3+b^3+c^3-3abc= 729-3(9)(23)=108