GRE Quant Ep 3: Coordinate Geometry

Do you mix up between parallel and perpendicular lines? Do you understand the basics of midpoints, slopes, intercepts, and distance formulas, but still somehow struggle with GRE coordinate geometry during the actual exam?

In this video, Harry -- a GMAT Ninja tutor -- will show you how to think about GRE coordinate geometry. He'll help you understand the content and how to apply the necessary formulas and processes to a GRE coordinate geometry question effectively and efficiently.

This is video #3 in our series of full-length GRE quant lessons. For updates on upcoming videos, please subscribe!

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Chapters:
00:00 Introduction
02:20 Question 1 - Horizontal & Vertical Lines
11:09 Question 2 - Midpoints & the Distance Between Points
21:54 Question 3 - Slopes, Intercepts & Equations of Lines
31:17 Question 4 - Slopes & Intercepts Part II
38:22 Question 5 - Parallel & Perpendicular Lines
45:10 Question 6 - Problem Solving in Coordinate Geometry
53:11 Question 7 - Comparing coordinates
59:49 Question 8 - Find the y-intercept

[artfulandtricky]

Thank you so much. Compared to the GMAT questions, the difficult level seems considerably easier. It would be great if you do a video covering: mixture, distance, and work word problems. Thanks!

[jesuslover]

I want to ask a question regarding the last question; if -b<0 how did you then get b>0.
Thank you.
Your videos are really helpful.

[HarshPatel-bvrz]

Another great video Harry! Great algebraic solution for Question 8. I did a graphical solution for each choice in my head and found it to be more efficient. Is this a good way to handle problems of this magnitude or can it result in errors?

[dariushsayson]

Amazing video. Question for you. On question #8, the line does not pass through the origin which is (0, 0). If it did pass through (0, 0), then x=0 would be the x-intercept of the line. Therefore, on answer choice C, because it says that the product of the slope of line m and its x-intercept is negative, this means that the x-intercept is either a positive number if the slope is negative, or a negative number if the slope is positive. Therefore, this would make answer choice C correct without doing any math because if the x-intercept passed through the origin, the product of the slope and the x-intercept would simply be 0. Did I interpret this correctly without having to do any algebra?

[leahtowery]

Thank you for these videos!! For question 4, wouldn't you want to double check that the point of intersection between the two lines corresponds with the graph? For example an answer choice that had a point of intersection with a positive x value would not work even if the slopes and intercepts aligned (in this case both B and D still work). Is this something we should look out for or is there a way to confirm this without doing the additional algebra?

[imransyed]

For question 6, why did you assume that the point of intersection of the two lines is directly above the exact midway point over 3.5 on the x axis? Because the lines you drew are rough estimates, not exact calculations, so what if the point of intersection was not directly above the midway point between the x axis of the two lines?

[imransyed]

For question 4, why did you assume the first column are the P equations and the second column is the Q equations, the question does not indicate which is which so how can depend for a correct answer on our assumption? What if I did the opposite and labeled the first column Q and the second column P, or what if I said they were all scattered and that each column could have an equation for both P and Q? Please answer I am confused

[Abkuyper]

57:23 'C is less than D' because they both Negative right?

[Abkuyper]

1:08, When the line does not go through the origin, it means that it is not Y=X right? thank you

[yessbenne]

straight line with linear equartion y=ax+b doenst cross the x line only if the slope m=0
distance racine((x1-x2)**2+(y1-y2)**2) and midpoint ((x1+x2)/2, (y1+y2)/2) formulat in x, y space