Test Prep

[moneyman]

The y intercept of line l is 4. If the slope of l is negative, which of the foll could be the x intercept of l?

(1) -1
(2) 0
(3) 6

Thanks

[sankruth]

(3) 6

[moneyman]

The Test Prep software is generous enough to give the answers of the questions!! So do you mind giving an explanation for your answer??

[camitava]

moneyman, I don't know how Sankruth chose the option - C. May be I am missing something! But to me, as the st line L is having a negative slope and Y-intercept is positive, I will go for A. So, the slope will come negative. Am I doing something wrong? What's the OA?

[Stuart@KaplanGMAT]

If the slope is negative, then the line goes from the top left to the bottom right.

Since the y-intercept is positive and the line is going from top left to bottom right, it will cross the x-axis at a positive coordinate.

Choose the only positive answer:

(3) 6

(Was this a roman numeral question?)

[Bronson]

If the slope is negative, then the line goes from the top left to the bottom right.

Can you explain this? What is negative or positive slope?

Thank you

[Stuart@KaplanGMAT]

Can you explain this? What is negative or positive slope?

Thank you

The slope of a line is how "slanted" it is. Slope is defined as rise/run or (change in y)/(change in x) = (Y2 - Y1)/(X2 - X1). Slope measures how quickly the line changes vertically (the y-value) compared to how quickly it changes horizontally (the x-value).

In the x-y coordinate plane, "up" and "right" are the positive directions. The top right quadrant has all positive coordinates (i.e. (+,+)) and the bottom left quadrant has all negative coordinates (i.e. (-,-)).

A line with a positive slope goes from bottom left to top right, since (change in y)/(change in x) is positive.

For example, if one point on the line were (-2, -4) and another point were (4, 10), the slope would be:

(change in y/change in x) = (-4 - 2)/(-2 - 10) = -6/-12 = 1/2

A line with a negative slope goes from top left to bottom right, since (change in y)/(change in x) is negative.

For example, if one point on the line were (-2, 4) and another point were (3, -6), the slope would be:

(change in y/change in x) = (4 - -6)/(-2 - 3) = +10/-5 = -2

[camitava]

Thanks Stuart! Now got the point?