Write the Word or Phrase That Best Completes Each Statement $\left(6 x^{2}+9 x^{4}+3 x^{3}+4 x+8\right) \div(6 x+8) ?$

Write the word or phrase that best completes each statement or answers the question.
-What must be done to the dividend before beginning the "long division" process for $\left(6 x^{2}+9 x^{4}+3 x^{3}+4 x+8\right) \div(6 x+8) ?$