Factor $LaTeX: \displaystyle 56 x^{3} - 64 x^{2} - 63 x + 72$ .

Grouping the first two terms and factoring out their GCF, $LaTeX: \displaystyle 8 x^{2}$ , gives $LaTeX: \displaystyle 8 x^{2}(7 x - 8)$ . Grouping the last two terms and factoring out their GCF, $LaTeX: \displaystyle -9$ , gives $LaTeX: \displaystyle -9(7 x - 8)$ . The polynomial now has a common binomial factor of $LaTeX: \displaystyle 7 x - 8$ . This gives $LaTeX: \displaystyle 8 x^{2} \left(7 x - 8\right) -9 \cdot \left(7 x - 8\right) = \left(7 x - 8\right) \left(8 x^{2} - 9\right)$ .