Test problem that stumped me. All points on same line?

Question

Hello, there was a problem on a recent test that I could not figure out. It was a problem that consisted of 3 graph points and an equation. It proceeded to ask if the points were on the same line or not. The equation looked like this (I don't remember the variable it was set equal to so I will just put Q.)     Q = A * B^x 

The three points were somewhere along the lines of (-3,-2), (1,6) and (9,1). (The exact points don't really matter, I just need to see how the process works.)

I ended up having to guess on this question, but I am very curious to see how to do this.

Answer 1

If a point is on the line the ordered pair that names it must be a solution to the equation. 

Substitute each pair - x value and y value - into the equation. If it solves the point is on the line.