A box with an open top is to be constructed from a rectangular piece of cardboard with dimensions 14 in. by 20 in. by cutting out equal squares of side x at each corner and then folding up the sides (see the figure). (a) Find a function that models the volume V of the box.
V(x) =

(b) Find the values of x for which the volume is greater than 250 in3. (Round your answers to three decimal places. Enter your answer using interval notation.)

(c) Find the largest volume that such a box can have. (Round your answer to three decimal places.)