Answer
$$ (2x-2x^2)\sqrt[4]{x+1}$$
Work Step by Step
In order to simplify the expression, we first simplify each of the terms, and then we combine like terms. Doing this, we find:
$$ \sqrt[4]{16x^4+16x^5}-2\sqrt[4]{x^8+x^9}\\ 2x\sqrt[4]{x+1}-2x^2\sqrt[4]{x+1}\\ (2x-2x^2)\sqrt[4]{x+1}$$
