Question

find the value of ab+bc+ac if a+b+c=9 and a²+b²+c²=35

Answer 1

hope this will help you

Answer 2

(a+b+c)² ⇒(9)²
(a²+b²+c²)+2(ab+bc+ac)⇒81
35+2(ab+bc+ac)⇒81
2(ab+bc+ac)⇒81-35
ab+bc+ac⇒46/2
ab+bc+ac⇒23