Factor $LaTeX: \displaystyle 80 x^{3} - 72 x^{2} - 40 x + 36$ .

Factoring out the GCF $LaTeX: \displaystyle 4$ from each term gives $LaTeX: \displaystyle 4(20 x^{3} - 18 x^{2} - 10 x + 9)$ . Grouping the first two terms and factoring out their GCF, $LaTeX: \displaystyle 2 x^{2}$ , gives $LaTeX: \displaystyle 2 x^{2}(10 x - 9)$ . Grouping the last two terms and factoring out their GCF, $LaTeX: \displaystyle -1$ , gives $LaTeX: \displaystyle -1(10 x - 9)$ . The polynomial now has a common binomial factor of $LaTeX: \displaystyle 10 x - 9$ . This gives $LaTeX: \displaystyle 4[2 x^{2} \left(10 x - 9\right) -1 \cdot \left(10 x - 9\right)] = 4\left(10 x - 9\right) \left(2 x^{2} - 1\right)$ .