Why should you not use the "simple" method?

If you really want to do it "the hard way", you can use "synthetic division":

-2) 1 0 -2 -1 ("1 0 -2 -1" are the coefficients of [tex]x^3- 2x- 1)

-2 4 -4

1 -2 2 -5 so A(x)= -5

where I brought down the first "1" to the third row then multiplied it by -2 to get the -2 in the second row and added it to 0 to get -2 in the third row, multiplied that by -2 to get the 4 in the second row, add that to -2, etc.

To multiply A and B, use the "distributive law":

and distribute again: