If the dependent variable of a quadratic function is exchanged for a constant, say $D,$ the result is a quadratic equation: This type of equation can be solved graphically. This is done by first plotting the function $y=a{x}^2+bx+c,$ then finding the $x$-coordinate of the point(s) on the graph that has the $y$-coordinate $D.$ The $x$-coordinate(s) is the solution to the equation.