For this case we have that by definition, the area of a square is given by:
![A = l ^ 2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/wwa1vdcatq4jkw1yvv6xt32rhh4hlk5stj.png)
Where "l" is the side of the square.
Let "x" be the variable that represents the side of a square.
So, the area of this square will be given by the following function:
![y = f (x)](https://img.qammunity.org/2020/formulas/mathematics/high-school/n64yh5douy1r1w3ttbnx9kpu5atg3zuu2a.png)
Where:
![f (x) = x ^ 2](https://img.qammunity.org/2020/formulas/physics/middle-school/unkk6eiz5gx1ra4acwi0u98tf6ky9vpuwd.png)
Answer:
![f (x) = x ^ 2](https://img.qammunity.org/2020/formulas/physics/middle-school/unkk6eiz5gx1ra4acwi0u98tf6ky9vpuwd.png)