Question

Evaluate ab+bc+ca . If a²+b²+c²=50 and a+b+c=12​

Answer 1

ab+bc+ac=47

Explanation:

(a+b+c)=12

Square both sides

a^2+b^2+c^2+2(ab+bc+ac)=144

2(ab+bc+ac)=94

ab+bc+ac=47

Answer 2

ab + bc + ca = 47

Explanation:

Using the algebraic identity

(a + b + c) = a² + b² + c² + 2(ab + bc + ca) , then

12² = 50 + 2(ab + bc + ca)

144 = 50 + 2(ab + bc + ca) ← subtract 50 from both sides

94 = 2(ab + bc + ca) ← divide both sides by 2

47 = ab + bc + ca