Math CentralQuandaries & Queries


Question from Danielle, a student:

Hello. I need some help with this: i am supposed to find the equation of a line with a point (2/3,5) and (-5/6,-4) the answer in the book says y=6x+1. My question is how did they get 6 for the slope?

Thank you!

Hi Danielle,

The slope is the difference between the y-coordinates divided by the difference between the x-coordinates in the same order.

Suppose the points are (2/5, -2) and (-3/10, 5). The slope is then

[5 - (-2)]/[-3/10 - 2/5] = 7/[-3/10 - 4/10] = 7/(-7/10) = -10

Now try your points,

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