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GMATPrep - xy-coordinate problem - can't visualise it!

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GMATPrep - xy-coordinate problem - can't visualise it!

by jsl » Sat Nov 08, 2008 7:27 am
In the xy-coordinate plane, line L and line K intersect at the point (4,3). Is the product of their slopes negative?

1) The product of the x-intercepts of lines L and K is positive
2) The product of the y-intercepts of lines L and K is negative

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Re: GMATPrep - xy-coordinate problem - can't visualise it!

by logitech » Sat Nov 08, 2008 9:10 am
jsl wrote:In the xy-coordinate plane, line L and line K intersect at the point (4,3). Is the product of their slopes negative?

1) The product of the x-intercepts of lines L and K is positive
2) The product of the y-intercepts of lines L and K is negative

OA C
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by bluementor » Mon Nov 10, 2008 2:59 am
Nice one Logitech!

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by jsl » Mon Nov 10, 2008 3:33 am
Thanks for the diagam - really appreciate it. However, am still a bit confused in working this one out. When you multiply two slopes together, do you basically get a slope which is in between the two?

Additionally, how do you know if the slope is negative or positive? If you multiply two sets of slopes which have +ve x-coordinates and +ve y-coordinates, you get a negative slope. In the same way, if you have two sets of slopes which have -ve x-coordinates and -ve y-coordinates, you get a negative slope.... does this basically prove the answer is always yes?
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by logitech » Mon Nov 10, 2008 9:23 am
jsl wrote:Thanks for the diagam - really appreciate it. However, am still a bit confused in working this one out. When you multiply two slopes together, do you basically get a slope which is in between the two?

Additionally, how do you know if the slope is negative or positive? If you multiply two sets of slopes which have +ve x-coordinates and +ve y-coordinates, you get a negative slope. In the same way, if you have two sets of slopes which have -ve x-coordinates and -ve y-coordinates, you get a negative slope.... does this basically prove the answer is always yes?
I see where you are coming from but both lines need to pass through (4,3). It limits our choices.
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by aj5105 » Fri Jan 16, 2009 2:39 am
(C)

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by aj5105 » Fri Jan 16, 2009 2:40 am
nice effort Logitech !
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