Write the Word or Phrase That Best Completes Each Statement $$( 4 \sqrt [ 3 ] { 7 } - 8 \sqrt { 2 } ) + ( ? ) = 6 \sqrt [ 3 ] { 7 } - 3 \sqrt { 2 }$$

Short Answer

Write the word or phrase that best completes each statement or answers the question.
-Find the missing radical expression. $$( 4 \sqrt [ 3 ] { 7 } - 8 \sqrt { 2 } ) + ( ? ) = 6 \sqrt [ 3 ] { 7 } - 3 \sqrt { 2 }$$