Factor $LaTeX: \displaystyle - 81 x^{3} + 63 x^{2} - 36 x + 28$ .

Factoring out the GCF $LaTeX: \displaystyle -1$ from each term gives $LaTeX: \displaystyle -(81 x^{3} - 63 x^{2} + 36 x - 28)$ . Grouping the first two terms and factoring out their GCF, $LaTeX: \displaystyle 9 x^{2}$ , gives $LaTeX: \displaystyle 9 x^{2}(9 x - 7)$ . Grouping the last two terms and factoring out their GCF, $LaTeX: \displaystyle 4$ , gives $LaTeX: \displaystyle 4(9 x - 7)$ . The polynomial now has a common binomial factor of $LaTeX: \displaystyle 9 x - 7$ . This gives $LaTeX: \displaystyle -1[9 x^{2} \left(9 x - 7\right) +4 \cdot \left(9 x - 7\right)] = -\left(9 x - 7\right) \left(9 x^{2} + 4\right)$ .