Math CentralQuandaries & Queries


Question from molly, a student:

I'm having a problem with the y=mx+b for our homework we have a table that goes from 0 to 6 , 1 to 7 and 2 to 8 and we have to make a equation of that. Please help.

Hi Molly,

Here is the table the way I see it.

x y
0 6
1 7
2 8

You want to find the equation y = mx + b that fits the points in the table. The values of m and b are fixed that is for this line there is one value for m and one for b. The values of x and y change for each point on the line. Look at the first point. When x = 0 you know that y = 6 so in the equation substitute x = 0, y = 6

6 = m times 0 + b

and hence

6 = b

Thus you know that the equation is y = mx + 6.

Now substitute the second point x = 1, y = 7 into the equation and solve for m. This will then give you the equation. You can use the third point as a check. When you substitute x = 2, y = 8 into the equation is the left side equal to the right side?


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