Simplify (-4b^2+8b)+(-4b^3+5b^2-8b)

$(- 4 b^{2} + 8 b) + (- 4 b^{3} + 5 b^{2} - 8 b)$

Remove parentheses.

$- 4 b^{2} + 8 b - 4 b^{3} + 5 b^{2} - 8 b$

Combine the opposite terms in $- 4 b^{2} + 8 b - 4 b^{3} + 5 b^{2} - 8 b$ .

Subtract $8 b$ from $8 b$ .

$- 4 b^{2} - 4 b^{3} + 5 b^{2} + 0$

Add $- 4 b^{2} - 4 b^{3} + 5 b^{2}$ and $0$ .

$- 4 b^{2} - 4 b^{3} + 5 b^{2}$

Add $- 4 b^{2}$ and $5 b^{2}$ .

$- 4 b^{3} + b^{2}$