Question

if a square + b square + c square equals to 250 and ab+bc+ca equals to 3 then find the value of a + b + c

Answer 1

using formula (a+b+c)^2= a^2+b^2+c^2+2(ab+bc+ca)
=250+2(3)
=256
(a+b+c)^2= 256
a+b+c= √256
= 16

Answer 2

a2+b2+c2=250
ab+bc+ca=3
therefore (a+b+c)2=a2+b2+c2+2(ab+bc+ca)
               (a+b+c)2         = 250 + 6
               (a+b+c)2         = 256
                 (a+b+c)          =square root (256)
                                        =16