14) (8−x²+2x)/(3a) − 3x²/(3a) =

\(\frac{8-x^2+2x}{3a}-\frac{3x^2}{3a}=\frac{8-x^2+2x-3x^2}{3a}=\frac{8+2x-4x^2}{3a}\).

Ответ: \(\frac{8+2x-4x^2}{3a}\)