subtract. (-3u + 6) - (9u^4 - 5u^3 + 8u^2 + 6u + 9)

Explanation:

Step1: Distribute the negative sign

[(-3u + 6)-9u^{4}+5u^{3}-8u^{2}-6u - 9]

Step2: Combine like - terms

Combine the (u) terms: (-3u-6u=-9u), and combine the constant terms: (6 - 9=-3) The result is (-9u^{4}+5u^{3}-8u^{2}-9u - 3)

Answer:

(-9u^{4}+5u^{3}-8u^{2}-9u - 3)