Quadratic Functions

Just as $z^n=z\cdot z\cdots z$ ($n$ times) for $z\in R,n\in N$, we now generalise linear functions to quadratic functions: $P(x)=ax^2+bx+c$, where $a,b,c\in R$ are constants and $a\ne0$. If $P(t)=0$ for some $t\in R$, $t$ is called a zero of $P$. The next two subsections develop the formula for finding every zero, and …