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In the xy-plane, line l passes through the point (−7, k)

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by gmat_guy666 » Thu Oct 16, 2014 11:07 am
In the xy-plane, line l passes through the point (−7, k). What is the value of the y-intercept of line l ?

(1) The x-intercept of line l is 4.

(2) Line l and line n are parallel and the equation of line n is y=x+5



Give that Line n passes through (-5,5);points obtained from the equation y=x+5

Line l is parallel to line n and passes through negative X coordinate -7 . Would this be not sufficient to prove that there will be a unique point in Y co-ordinate where line l will pass through . Hence , B howeve, OA is C
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Source: — Data Sufficiency |

by [email protected] » Thu Oct 16, 2014 11:29 am
Hi gmat_guy666,

In Fact 2, we're told that lines L and N are parallel, which just means that they have the SAME SLOPE.

*You might find that drawing some quick sketches would help to visualize this prompt.*

Line N --> Y = X + 5 (the slope = 1)

Line L --> Y = X + B (we don't know what the Y intercept is)

With a slope of 1, as the lines "go to the left", both lines will eventually hit a point at which X = -7. Unfortunately, there are an infinite number of possibilities for the equation of Line L (and each would have a different Y-intercept). Thus, Fact 2 is INSUFFICIENT.

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Rich
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by Mathsbuddy » Fri Oct 17, 2014 8:58 am
Fact 1: Insufficient (as infinite values for k)
Fact 2: Insufficient (as infinite parallel lines)
Both facts: sufficient
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