Question

if a+b+c=15 and a^2+b^2+c^2=83 find the value of a^3+b^3+c^3-3abc

plz help a good answer will get a reward of brainlieast answer....

Answer 1

a³ + b³ + c³ - 3abc = (a + b+ c)(a² + b² +c² -ab - bc - ac)

(a + b + c)² = a² + b² + c² + 2ab + 2bc + ac

2(ab + bc + ac) = 15² - 83 = 225 - 83 = 142

ab + bc+ ac = 142/2 = 71

a³ + b³ + c³ - 3abc = (15)(83 - (71) = 15 x 12 = 180