To find the root of an equation, for example, $2x^2-6x-4=0,$ we can calculate the function value $f(x)=2x^2-6x-4$ with an initial guess of $x=0,$ then increase $x$ by a certain step $($say $0\mathrm{.}1)$ and calculate the function value again. Continue this procedure until $f(x)$ changes sign from $-$ to or$,+$ to $-$