To simplify this equation, you would first distribute the (x+2) to the terms inside the parentheses:

(x+2)(x²-2x+4) = x³ - 2x² + 4x + 2x² - 4x + 8
x³ + 2x - 4

Next, distribute the -x² to the terms inside the parentheses in the second part of the equation:

-x²(x+2) = -x²(x) -x²(2)
-x³ - 2x²

Now, substitute the simplified expressions back into the original equation:

(x³ + 2x - 4) - (x³ + 2x²) = 0
x³ + 2x - 4 - x³ - 2x² = 0
2x - 4 - 2x² = 0

This equation can be further simplified to:

-2x² + 2x - 4 = 0

This is the final simplified form of the equation.