Question

if a2+b2+c2=20 and ab+bc+ca=8 find a+b+c​

Answer 1

Answer:

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

(a+b+c)^2=20+2×8

a+b+c=root 36

a+b+c=6.