Experiment with various viewing windows to determine the zeros of $f(x)=2 x^4 + 3 x^3 - 20 x^2 - 27 x + 18$. Then write $f$ in factored form.

(a) The factor which corresponds to the zero that has the smallest value is $(x -$ $)$.

(b) The factor which corresponds to the zero that has the second smallest value is $( x -$ $)$.

(c) The factor which corresponds to the zero that has the largest value is $( x -$ $)$.

(d) The remaining factor is of the form $($ $x - 1 )$.