The shape of the graph of a quadratic function is a parabola, which is like a letter U. One half of the parabola is a mirror image of the other half. Because the coefficient of $\displaystyle{{x}}^{{2}}\usepackage{cmbright}\Huge\$ is $\displaystyle-{1}\usepackage{cmbright}\Huge\$ , the parabola opens downward. Because $\displaystyle{f{{\left({0}\right)}}}={0}\usepackage{cmbright}\Huge\$ , the point $\displaystyle{\left({0},{0}\right)}\usepackage{cmbright}\Huge\$ is on the graph.