Write down the equation for which you'd like to calculate the average slope. For example, let's use f(x)=x²+2x-1.
Write the formula for average slope on your paper. It is the following:
A= (f(x) - f(a)) / (x - a)
A stands for the average slope. (x-a) stands for the change in the input, and (f(x) - f(a)) stands for the change in output, the f representing the function.
Choose values for x and a. Depending on the equation, the points that you choose can have a great effect on the calculation's outcome. The points you choose determine the section of the graph that you are calculating the slope of. In our example, let's choose x=3 and a=0.
Plug a and x first into the function to calculate f(x) and f(a). In our example, this gives us f(x)=3² + 2(3) - 1=14 and f(a)=0² + 2(0) - 1= -1.
Plug those answers into the average slope equation. This gives us A = (14 - (-1)) / (3 - 0) = 5. So the average slope of the equation between the two points is 5.