Let's write in expanded form: <math><msup><mrow><mo>(</mo><mi>x</mi><mo> + </mo><mn>3</mn><mo>)</mo></mrow><mrow><mn>2</mn></mrow></msup></math>
 <math><mo>(</mo><mi>x</mi><mo> + </mo><mn>3</mn><mo>)</mo><mo>·</mo><mo>(</mo><mi>x</mi><mo> + </mo><mn>3</mn><mo>)</mo></math>
 <math></text><text><mi>x</mi><mo>·</mo><mi>x</mi></text><text><mo> + </mo><mi>x</mi><mo>·</mo><mn>3</mn></text><text><mo> + </mo><mn>3</mn><mi>x</mi></text><text><mo> + </mo><mn>3</mn><mo>·</mo><mn>3</mn></text><text></math>

▷<b>Answer: &nbsp; <math><msup><mrow><mi>x</mi></mrow><mrow><mn>2</mn></mrow></msup><mo> + </mo><mn>6</mn><mi>x</mi><mo> + </mo><mn>9</mn></math></b><span style='font-size:smaller'> &nbsp; &nbsp; (processing: 3 steps, 1 ms)</span>