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ACT Math 2.3 Coordinate Geometry 279 Views
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Description:
ACT Math: Coordinate Geometry Drill 2, Problem 3. What is the equation of the graph in the video?
Transcript
- 00:02
And here's an unshmoopy question you may find on an exam somewhere in life...
- 00:06
What is the equation of this graph?
- 00:08
And here are your potential answers...
- 00:14
Alright... remember our old friend y equals mx plus b? It's the standard form to describe a line.
- 00:19
And the Rosetta stone in it is m. That is, the slope.
Full Transcript
- 00:23
Since we have 2 points on this line, we can get that sucker straight away.
- 00:28
So... remember that slope is rise over run, or y2 minus y1 over x2 minus x1.
- 00:33
That'll give us a slope of 3 over -1.5 or just ... -2.
- 00:40
Now that we know m is -2, we can plug it into our equation to get y equals -2x plus b.
- 00:46
Now to find b...
- 00:48
To do that, we can just plug in one of the points. So let's just use 0, 3.
- 00:52
0 is the x value and 3 is the y value.
- 00:55
Plug in the variables and we get:
- 00:57
3 equals -2 times 0 plus b.
- 01:02
Well, -2 times 0 is 0... so b equals 3.
- 01:06
And our answer is C.
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