This is a problem in either long division
or synthetic division, depending on which
you are studying.

Write 3x³ - 5 as 3x³ + 0x² + 0x - 5

By long division:

            3x² + 3x + 3
x - 1)3x³ + 0x² + 0x - 5
      3x³ - 3x²
            3x² + 0x
            3x² - 3x
                  3x - 5
                  3x - 3
                      -2

So using the formula:






or



Do you understand the steps in long division?
If not post again, asking to list the steps.

By synthetic division:

1 | 3  0  0  -5
  |    3  3   3
    3  3  3  -2

Which is interpreted as 



Do you understand the steps in synthetic
division, if that is what you are
studying? If not post again asking
to go through the steps.

Edwin