Question

If a+b+c=9 and ab+bc+ca-26 find a²+b²+c²?​

Answer 1

we have :

(a+b+c)² = a² + b² + c² + 2(ab+bc+ca)

a+b+c= 9

and

ab+bc+ca = 26

Substituting the values in the above formula,

We get,

9² = a² + b² + c² + 2×26

81 = (a² +b² +c²) + 52

(a² +b²+c²) = 81-52

(a²+ b² + c²) = 29 is a required answer.