Question

19. a+b+c=10, ab+bc+ca=20, then a'+b'+c=
A) y = 4
B)x= 4
C) y = 4
D) None​

Answer 1

Answer:

( a+ b + c) 2 = a2 + b2 + c2 + 2 ( ab + bc + ac)

ab + bc + ac = --20 / 2 = -10