Question

If a + b + c = 8, a b + bc + ca equal 19 then find a square + b square + c square

Answer 1

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

⇒ 8² =  a² + b² + c² + 2 x 19

So,

a² + b²+c² = 64 - 38 = 26