Question

If a+b+c=9 and ab+bc+ca=23, find the value of a2+b2+c2

Answer 1

(a+b+C)^2=a^2+b^2+c^2+2(ab+bc+ca)
9^2=a^2+b^2+c^2+2×23
81=a^2+b^2+c^2+46
81-46=a^2+b^2+c^2
35=a^2+b^2+c^2(answer)

Answer 2

(a+b+c)^2= (9)^2 =81

a^2+b^2+c^2+2×23 =81

a^2+b^2+c^2=81-46

a^2+b^2+c^2 = 35

HOPE IT HELPS YOU
HAVE SWEET DREAMS.