[tex](4x - 3)(3x^2 - 4x - 3)[/tex]
[tex]=4x\cdot \:3x^2+4x\left(-4x\right)+4x\left(-3\right)-3\cdot \:3x^2-3\left(-4x\right)-3\left(-3\right)[/tex]
[tex]=4x\cdot \:3x^2-4x\cdot \:4x-4x\cdot \:3-3\cdot \:3x^2+3\cdot \:4x+3\cdot \:3[/tex]
[tex]\mathrm{Simplify}\:4x\cdot \:3x^2-4x\cdot \:4x-4x\cdot \:3-3\cdot \:3x^2+3\cdot \:4x+3\cdot \:3:\quad 12x^3-25x^2+9[/tex]
[tex]=12x^3-25x^2+9[/tex]