The option to input an equation is at the top-right corner of the calculator window. As you can see from the picture above, you can compute both linear and quadratic equations in the calculator.

A linear equation is drawn as a straight line on a set of axes. To draw the graph we need coordinates. We generate these coordinates by substituting values into the linear equation. STEP 1 - Draw ...

In particular, they show that any quantum computation can be encoded into an instance of solving linear equations, even with the restrictions required for their quantum solver to be efficient.