Question

if a square + b square + c square equal to 50 and a b + BC + is equal to 47 find a + b + c is the answer A + B + c equal to plus minus 12

Answer 1

We know that
(a + b + c)² = a² + b² + c² + 2(ab + bc + ca)
Given a² + b² + c² = 50 and ab + bc + ca = 47.
Therefore
(a + b + c)² = 50 + 2(47)
                   = 50 + 94  
                   = 144
a + b + c = √144 = + or - 12 

Hope this helps you.