Write the Word or Phrase That Best Completes Each Statement $$f ( x ) = 2 x ^ { 3 } + 5 x ^ { 2 } - x + 6$$

Essay

Write the word or phrase that best completes each statement or answers the question.
Provide the missing information.
-Explain why the number 7 cannot be a rational zero of the polynomial $$f ( x ) = 2 x ^ { 3 } + 5 x ^ { 2 } - x + 6$$