I fell in to that trap as well on first glance. But here's the best I can do:relaxin99 wrote:ax + b = 0, is x>0?
(1) a + b > 0
(2) a - b > 0
The anwer is E, i thought it is C. can someone please explain
ax + b = 0
ax = -b
a = -b/x
1) Since a + b > 0, and ax + b = 0, then (x-1)*a must be negative. That doesn't help us determine the sign of x: all we know is that either (x-1) < 0 or a < 0.
2) a > b. I tried to get something useful out of it but I couldn't; this may be a failure on my part.
1) & 2) a > 0. This still only implies that bx < 0, which isn't sufficient to show that x > 0.
I'm not convinced by my answer, but it's the best I've got. Hopefully someone will elaborate.
