### Home > A2C > Chapter 4 > Lesson 4.2.1 > Problem 4-64

There are several ways to write the equation. It depends on how you decide to draw the *x*- and *y*-axes.

The *y*-axis could go through the point where the water leaves the hose at (0, 4). On the other hand you could put the *y*-axis through the vertex and place the *x*-axis so that the nozzle is at (−4, 0). Still another possibility is to make the vertex the point (0, 0).

Use the general equation of a parabola in graphing form: *y* = *a*(*x* − *h*)^{2} + *k*

After you've filled in the values for *h* and *k*, you will need to substitute one point (*x*, *y*) in order to solve for *a*. Then you will be able to write the equation.

Use the eTool below to check your work.

Click the link at right for the full version of the eTool: A2C 4-64 HW eTool