Factor $LaTeX: \displaystyle 28 x^{3} - 8 x^{2} - 21 x + 6$ .

Grouping the first two terms and factoring out their GCF, $LaTeX: \displaystyle 4 x^{2}$ , gives $LaTeX: \displaystyle 4 x^{2}(7 x - 2)$ . Grouping the last two terms and factoring out their GCF, $LaTeX: \displaystyle -3$ , gives $LaTeX: \displaystyle -3(7 x - 2)$ . The polynomial now has a common binomial factor of $LaTeX: \displaystyle 7 x - 2$ . This gives $LaTeX: \displaystyle 4 x^{2} \left(7 x - 2\right) -3 \cdot \left(7 x - 2\right) = \left(7 x - 2\right) \left(4 x^{2} - 3\right)$ .