Bài 4
a) Có: \(\left(2x+3\right)\left(4x^2-6x+9\right)-2\left(4x^3-1\right)\)
\(=8x^3-27-8x^3+2\)
\(=\left(8x^3-8x^3\right)-\left(27-2\right)\)
\(=-25\)
Vậy...
b) Có: \(\left(4x-1\right)^3-\left(4x-3\right)\left(16x^2+3\right)\)
\(=64x^3-48x^2+12x-1-64x^3-12x+48x^2+9\)
\(=\left(64x^3-64x^3\right)-\left(48x^2-48x^2\right)+\left(12x-12x\right)+\left(9-1\right)\)
\(=8\)
Vậy...