$\left( x+3 \right) \times \left( x+3 \right)$
Multiply each term in the first parentheses by each term in the second parentheses (FOIL)$x \times x+3x+3x+3 \times 3$
The factor $x$ repeats $2$ times, so the base is $x$ and the exponent is $2$${x}^{2}+3x+3x+3 \times 3$
Multiply the numbers${x}^{2}+3x+3x+9$
Collect like terms${x}^{2}+6x+9$