Question

a+b+c=7 and ab+bc+ca=20 find the value of a²+b²+c²

Answer 1

the value of that equation is 9

Answer 2

(a+b+c) whole square=a×a+b×b+c×c+2(ab+BC+ca)
7×7=a×a+b×b+c×c+2(20)....ab+BC+ca=20
49-40=a×a+b×b+c×c
9 is answer