Jephter M. answered 01/10/20
Tutoring for all levels of math for high school and undergrad college
I am assuming here that the table in question is the following:
| x | y |
| 0 | 3 |
| 3 | 9 |
| 6 | 15 |
| 10 | 23 |
You only need two of those points in order to come up with the equation of the corresponding line.
We’ll solve the problem in 2 ways
1. Solution in y-intercept form y=mx+b
We can calculate the slope of the line using any 2 of the given points: I pick (0,3) and (3,9) . Recall the formula for finding the slope of the line through 2 points (x1,y1) and (x2,y2) as m=(y2-y1)/(x2-x1)
By plugging in the corresponding values, we get (9-3)/(3-0)=6/3=2
Since we now the value of y when x is zero, i.e. the point (0,3) of the table, then the value of b is 3.
Now, putting everything together, we have y=2x+3
2. Solution in point-slope form y-y1=m(x-x1)
You can proceed the same way above to find the slope m=2
Now use one of the points in the given table to plug into x1 and y1
Doing the last 2 steps will result in y-23=2(x-10) if you use the point (10,23)
Realize that the point slope form of the equation of a line is not unique since using a different point will result in different values of x1 and y1. That said y-3=2(x-0) would also be a valid answer in the point-slope form.