Question

a+b+c=9 and ab+ bc+ ca=26 then find the value of a^2+b^2+c^2

Answer 1

We know that

(a+b+c)^2 = a^2 +b^2 +c^2 +2ab+2bc+2ca

(a+b+c)^2=a^2+b^2+c^2 +2(ab+bc+ca)

Now,

We have

a+b+c=9

ab+bc+ca=26

So,

9^2 = a^2 + b^2 +c^2 +2(26)

81=a^2 +b^2 +c^2 + 52

81-52 =a^2 + b^2 + c^2

29 = a^2 + b^2 + c^2

$\bf{\huge{So\:your\:answer\: is\:29}}$

$\bf{Hope\:it\:helps}$