a + bc = -1

Question

b + ac = -1
c + ab = -1

Which of these values of 'a' is one solution for this system of equations?

A) -2
B) -1
C) 0
D) 2

Please also explain how you got the answer, thanks.

Answer 1

rewrite as
b = -(a+1)/c
b = -(1+ac)
b = -(c+1)/a

Now eliminate b:

-(a+1)/c = -(1+ac)
-(c+1)/a = -(1+ac)

Now eliminate c, and you end up with a = -2 or 1