I need help with math, please tell me how you got your answer

Question

Find the product of  and  , and write the expression in its most simplified form.

SHOW ALL WORK AND STEPS (Or explain) so you can receive partial credit. 

Answer 1

-4x^3 -2x^2 +2x -5 times 3x-4 = -12x^4 +10x^3 +14x^2 -23x +20

it's like long division, keep everything in columns in the same way

-4 -2 2 -5

____3 - 4

16 8 -8 20 is -4 times the first row

-12 -6 6 -15 is 3 times the first row; now add the columns

-12 +10+14-23+20

translate that to

-12x^4+10x^3+14x^2-13x+20

It's similar to arithmetic multiplication where each column represents 10,000's, 1000's, 100's 10's and 1's

only here they represent x^4, x^3, x^2, x and constants