Question

If a 2 +b 2 +c 2 =250 and ab+bc+ca=3, find a+b+c.

Answer 1

(a+b+c)2 = a2+ b2+ c2+ 2(ab+bc+ca)
(a+b+c)2 = 250 + 2(3)          (a2+b2+c2=250 and ab+bc+ca= 3)
(a+b+c)2 = 256
(a+b+c)= root 16
(a+b+c) = 16

Answer 2

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

( a + b + c )^2 = 250 + 2 × 3

( a + b + c )^2 = 256

( a + b + c )^2 = ( ± 16)^2

( a + b + c )^2 = ± 16