4. Describe how you can tell by looking at the graph of a function which variable is the input variable and which is the output variable.

The variable in the vertical axis (or y-axis) is the output

The variable in the horizontal axis (or x-axis) is the input.

Step-by-step explanation:

Usually, a graph of a function y = f(x) is represented in an X-Y coordinate axis.

An X-Y coordinate axis is conformed by two perpendicular lines, one vertical (y-axis) and one horizontal (x-axis)

The vertical axis (or the y-axis) is the output, and the horizontal axis (or the x-axis) is the input.

This method will work almost always, as is standardized that the x-axis corresponds to the input, and the y-axis corresponds to the output.

just take the area of the square and then the area of the circle then subtract the circle area from the squares area

step-by-step explanation: