vk_vinayak wrote:If v ≠0, is v > 0 ?
(1) vw = 16
(2) v + w = -10
[spoiler]OA: C[/spoiler]
Anurag's is the preferred method here (fast and accurate).
However, if you didn't see that fast/logical approach, here's the longer/algebraic approach.
Target question:
Is v > 0 ?
Statement 1: vw = 16
Lots of possible values for v and w. Here are two.
case a: v = 1, w = 16, which means v
is greater than zero
case b: v = -1, w = -16, which means v is
not greater than zero
So, statement 1 is NOT SUFFICIENT
Statement 2: v + w = -10
Lots of possible values for v and w. Here are two.
case a: v = 1, w = -11, which means v
is greater than zero
case b: v = -1, w = -9, which means v is
not greater than zero
So, statement 2 is NOT SUFFICIENT
Statements 1 + 2:
Take v + w = -10 and solve for w to get: w = -10 - v
Take vw = 16 and replace w with -10 - v to get: v(-10 - v) = 16
Solve for v...
v(-10 - v) = 16
-10v - v^2 = 16
v^2 + 10v + 16 = 0
(v+2)(v+8) = 0
v = -2 or -8
Here, we can see that
v is definitely not greater than zero
Answer =
C
Cheers,
Brent
