Question

if (a+b+c)=9 and ab +bc + ca = 26 find a^2+b^2+c^2

Answer 1

Find: a² + b² + c²
If: (a+b+c) = 9                    ab +bc + ca = 26

      (a + b + c)² = 9²
⇒ a² + b² + c² + 2(ab + bc + ca)  = 81
⇒ a² + b² + c² + 2(26)  = 81
⇒ a² + b² + c² + 52  = 81
⇒ a² + b² + c²   = 81 − 52

⇒ a² + b² + c²   = 29

Answer 2

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

a^2+b^2+c^2=(9)^2-2(26)
=81-52
=29....



answer may be helps u