BTGModeratorVI wrote: ↑Wed Feb 03, 2021 10:29 am
In the xy-plane, if line k has negative slope and passes through the point (-5,r) , is the x-intercept of line k positive?
(1) The slope of line k is -5.
(2) r > 0
Answer:
E
Source: official guide
Target question: Is the x-intercept of line k positive?
When I scan the two statements, I can see that, if r is POSITIVE, then the point (-5, r)
can be very close to the x-axis or the point (-5, r)
can be very far from the x-axis.
Given this, let's go straight to the statements COMBINED, and see if we can find two cases that yield DIFFERENT answers to the
target question.
CASE A: If r =1, then the point (-5, r) is very close to the x-axis, and we get something like this:
In this case, the answer to the target question is
NO, the x-intercept of line k is NOT positive
CASE B: If r =50, then the point (-5, r) is far from the x-axis, and we get something like this:
In this case, the answer to the target question is
YES, the x-intercept of line k IS positive
Since we cannot answer the
target question with certainty, the combined statements are NOT SUFFICIENT
Answer: E
Cheers,
Brent
