r(x) = –x² + 3x s(x) = 2x + 1(s – r)(x) =

By definition, (s − r)(x) = s(x) − r(x). Substitute s(x) = 2x + 1 and r(x) = −x² + 3x to get (2x + 1) − (−x² + 3x), which matches choice C. Distributing the subtraction gives x² − x + 1.

AI-written and checked against the verified answer.