Which expression is equivalent to 9 x minus open paren x minus 8 close paren times open paren x plus 1 close paren plus 10 x ?

First expand the product: (x − 8)(x + 1) = x² − 7x − 8. Subtracting it gives −x² + 7x + 8, and adding 9x + 10x combines the x-terms to 26x. The expression is −x² + 26x + 8, which is choice D.

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