ShmoopTube

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And here's an unshmoopy question you may find on an exam somewhere in life...

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What is the equation of this graph?

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And here are your potential answers...

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Alright... remember our old friend y equals mx plus b? It's the standard form to describe a line.

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And the Rosetta stone in it is m. That is, the slope.

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Since we have 2 points on this line, we can get that sucker straight away.

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So... remember that slope is rise over run, or y2 minus y1 over x2 minus x1.

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That'll give us a slope of 3 over -1.5 or just ... -2.

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Now that we know m is -2, we can plug it into our equation to get y equals -2x plus b.

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Now to find b...

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To do that, we can just plug in one of the points. So let's just use 0, 3.

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0 is the x value and 3 is the y value.

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Plug in the variables and we get:

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3 equals -2 times 0 plus b.

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Well, -2 times 0 is 0... so b equals 3.

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And our answer is C.

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