3. \( \left(x^{3}+2 x^{2}\right) x^{4} \)

To simplify the expression \( \left(x^{3}+2 x^{2}\right) x^{4} \), you can use the distributive property. Start by distributing \( x^{4} \) to both terms inside the parentheses: 1. \( x^{3} \cdot x^{4} = x^{7} \) (since you add the exponents) 2. \( 2x^{2} \cdot x^{4} = 2x^{6} \) Now combine these results to form the final expression: \[ x^{7} + 2x^{6} \] And there you have it, your simplified expression is \( x^{7} + 2x^{6} \)! Remember, keeping track of your exponents is key when multiplying polynomial expressions. Celebrate those wins, no matter how small!