The given poly. has 3 terms. You may divide each one by x^3, one at a time.
For example, 3x^4 divided by x^3 equals 3x. That's the first term of your answer.
Next, divide x^3 into -6x^2. Writing this out, we get -6x^2
---------
x^3
The larger power of x is in the denominator, so the fraction reduces to
-6
------
x
This is your second term.
Try finding the 3rd term (that is, the 3rd quotient).
Write out your final answer in this format:
3x - 6/x - [ ? ]