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Coordinate Geometry Videos 38 videos
In geometry, points are called collinear if they all lie on the same line. What, no bunk beds?
ACT Math 4.5 Coordinate Geometry 200 Views
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Description:
ACT Math: Coordinate Geometry Drill 4, Problem 5. What is the equation of the graph in the video?
- Coordinate Geometry / Graphing equations
- Coordinate Geometry / Graphs of points, lines, polynomials, and circles
- Product Type / ACT Math
- Foreign Language / Arabic Subtitled
- Foreign Language / Korean Subtitled
- Foreign Language / Chinese Subtitled
- Foreign Language / Spanish Subtitled
- Coordinate Geometry / The relations between equations and graphs
Transcript
- 00:02
Here's your shmoop du jour, brought to you by Line Equations. Whose Line Equation is
- 00:07
it anyway? What is the equation of this graph?
- 00:11
And here are your potential answers...
- 00:17
This graph shows us the two points of intersection; they are here at point 5 on the x-axis...
- 00:22
and here at 2 on the y axis. So right off the bat, we know that 2 points
Full Transcript
- 00:27
on the line are .5, 0 and 0, 2. And since the line slopes downward, we know
- 00:34
its slope will be negative.
- 00:36
Now back to our old friend y equals mx plus
- 00:38
b, the standard form of a line. We can get the slope m by doing the
- 00:43
y over x dance like this...
- 00:45
and we get y2 minus y1 over x2 minus x1...
- 00:48
...or 2 minus 0 over 0 minus .5... ...which equals negative 2 divided by a half
- 00:54
or... negative 4. So we have y equals negative 4 times x plus
- 00:58
b...and we can just plug in some points to get b. Let's try the 2nd point - zero, 2
- 01:05
We have 2 equals negative 4 times 0 plus b or... 2 equals... b.
- 01:10
Which is answer C.
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