Question

if a+b+c=15 and ab+bc+ca=15,find the value of a^2+b^2+c^2

Answer 1

Given :

a + b + c = 15

and

ab + bc + can = 15

So , We have formula ,

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

(15)² = a² + b² + c² + 2(ab + bc + ca) [ Given ]

225 = a² + b² + c² + 2 ( 15 ) [ Given ]

225 = a² + b² + c² + 30

a² + b² + c² = 225 -30

So , a² + b² + c² = 195

Answer is 195

Hope it helped...