The square function is also known as the quadratic function, the second degree function, or simply called a parabola.

The bare quadratic function has the form: \[ f(x)=x^2. \]

• Inverse of $\sqrt{x}$.
• Never negative: $x^2 \geq 0$, for all $x\in \mathbb{R}$.
• The quadratic function is two-to-one since it sends both $x$ and $-x$ to $x^2=(-x)^2$.
• The quadratic function is convex, i.e., it curves upwards.