WeBWorK using host: https://webwork-ptx.aimath.org, format: simple seed: 134

We can use the formula $~y=a(x-x_v)^2+y_v~$ if we know the and one other point.

We can use the formula $~y=a(x-r_1)(x-r_2)~$ if we know the and one other point.

Otherwise, we must know at least points on the graph.

In that case, we use to solve for the parameters of the equation.