1. **State the problem:** Simplify the expression $(x-4)x^2$. 2. **Recall the distributive property:** To simplify expressions like this, multiply each term inside the parentheses by $x^2$. 3. **Apply the distributive property:** $$ (x-4)x^2 = x \cdot x^2 - 4 \cdot x^2 $$ 4. **Simplify each term:** $$ x \cdot x^2 = x^{1+2} = x^3 $$ $$ -4 \cdot x^2 = -4x^2 $$ 5. **Write the final simplified expression:** $$ x^3 - 4x^2 $$ This is the simplified form of the given expression.