please show the steps to solve this problem

.. (3x  1)(4x^2  2x  1)
= (3x)(4x^2  2x  1)  (4x^2  2x  1)
= 12x^3  6x^2  3x  4x^2 + 2x + 1
= 12x^3  6x^2  4x^2  3x + 2x + 1
= 12x^3  (6 + 4) x^2 + ( 3 + 2) x + 1
= 12x^3  10x^2  x + 1
= (3x)(4x^2  2x  1)  (4x^2  2x  1)
= 12x^3  6x^2  3x  4x^2 + 2x + 1
= 12x^3  6x^2  4x^2  3x + 2x + 1
= 12x^3  (6 + 4) x^2 + ( 3 + 2) x + 1
= 12x^3  10x^2  x + 1