Question

If a + b + c = 29 and a 2 + b 2 + c 2 = 791, find ab + bc + ca

Answer 1

PLEASE GIVE ME A BRANLIAST ANSWER AND FOLLOW

(a + b + c) ²= a²+b²+c²+2(a+b+c)

(29)²=791+2(a+b+c). put the value of a + b + c

and a² + b² + c²

841 = 791+2(ab+bc+ac)

841 –791=2(ab+bc+ac)

50=2(ab+bc+ac)

ab+bc+ac = 50/2=25