We can determine if a graph is a function or not using the Vertical Line Test. Since we see that 1 and 2 pass but 3 and 4 pass, 1 and 2 are functions while 3 and 4 are not.
Set f ( x ) = 0 f(x)=0. If the polynomial function is not given in factored form: Factor out any common monomial factors. Factor any factorable binomials or trinomials. Set each factor equal to zero and solve to find the x x- intercepts.
