Intermediate Algebra (6th Edition)

The direction of the opening of the parabola is determined by the sign of the coefficient of the squared term and whether the squared term is $x$ or $y$. If the equation is in the form: $y=ax^2+bx+c$, $\gt0 \longrightarrow$ Opens up $y=ax^2+bx+c$, $\lt0 \longrightarrow$ Opens down $x=ay^2+by+c$, $a\gt0 \longrightarrow$ Opens right $x=ay^2+by+c$, $a\lt0 \longrightarrow$ Opens left Using these rules, we get the parabola to open up.