[tex](2x - 1) {}^{3} (2x + 1) {}^{3} = ((2x - 1)(2x + 1) {}^{3 } = (4 {x}^{2} - 1) {}^{3} =(4 {x}^{2} ) {}^{3} - 3 \times (4 {x}^{2} ) {}^{2} \times 1 + 3 \times 4 {x}^{2} \times 1 {}^{2} - 1 {}^{3} = 64x {}^{6} - 48x {}^{4} + 12 {x}^{2} - 1[/tex]