Recall a linear function, is a line on a graph made up of an infinite amount of points which satisfy the relationship. That means at x=3 there is a specific point on the line with an output. The value of a function at x=3 asks, what is the output y value for the input x value?
To find it, we locate 3 on the x-axis. We draw a vertical line directly to the line following the grid line. We mark the point on the line. We then draw a horizontal line directly to the y-axis following the grid line. The point we hit on the y-axis is the value of the function.
