The vertical line test can be used to determine whether a graph represents a function. ... If we can draw any vertical line that intersects a graph more than once, then the graph does not define a function because that x value has more than one output. A function has only one output value for each input value.
Yes, there is an expanded algorithm for synthetic division involving nonlinear and non-monic divisors (check out the w.i.k.i.pedia page on "synthetic division", under the "Expanded sythetic division" section).
