Question: Line M's Slope

Comment on Line M's Slope

At step 3, another option, instead of cross multiplication, to -3 (c-d)=4 (6)
(-2/-2)*-3/4=6/c-d)
(6/-8)=6/(c-d)
Therefore -8=c-d
greenlight-admin's picture

That also works - nice job!

At step 3, another option is to mentally consider that if (-6/c-d) is the 3/4 of something, then 1(c-d) would equal -8. This saved me time in calculating/comparing quantities A & B.
greenlight-admin's picture

Nice approach!

On some previous slope questions I have seen the slope formula "y2-y1/x2-x1" used as "y1-y2/x1-x2" - does the order of the y's and x's matter?
greenlight-admin's picture

Great question!

As long as you use the same order, then either formula works.

This should make sense, since the way in which we label the coordinates is arbitrary.

For example, is we want to find the slope of the line between the points (1, 8) and (3, 5), we have two options:

1) We can say that x1 = 1 , y1 = 8, x2 = 3 and y2 = 5
OR
2) x1 = 3 , y1 = 5, x2 = 1 and y2 = 8

Since the labeling should have no effect on the slope of he line between the points (1, 8) and (3, 5), either formula will work.

Cheers,
Brent

In the previous question set I encountered a formula, y=mx+b
Can you please explain what that is?
greenlight-admin's picture

We call that form of an equation "slope y-intercept form"
It's all covered here: https://www.greenlighttestprep.com/module/gre-algebra-and-equation-solvi...

Cheers,
Brent

I am using this formula: slope= y2-y1/x2-x1, and still getting correct answers. How is that possible?

Thanks,
Ketan
greenlight-admin's picture

Slope = y2-y1/x2-x1 and slope = y1-y2/x1-x2 will both yield the same results.
Give it a try.

Cheers,
Brent

Have a question about this video?

Post your question in the Comment section below, and a GRE expert will answer it as fast as humanly possible.

Change Playback Speed

You have the option of watching the videos at various speeds (25% faster, 50% faster, etc). To change the playback speed, click the settings icon on the right side of the video status bar.

Let me Know

Have a suggestion to make the course even better? Email us today!

Free “Question of the Day” emails!