Linear interpolator help
The x input values must be unique and the y values must be unique. This means the same number cannot appear twice in the x column or twice in the y column.
Exactly one box must be empty before clicking the Calculate button.
A straight line through (x1, y1) and (x2, y2) satisfies
To see why this is true, stick in x1 and x2 and see that you get y1 and y2 out. If a linear fit is correct at two different points, it's correct everywhere.
So if we set x equal to x3, then
Solving for x3 we see that