Simplify 3x^9y^9*6x^4

$3 x^{9} y^{9} \cdot 6 x^{4}$

Multiply $x^{9}$ by $x^{4}$ by adding the exponents.

Move $x^{4}$ .

$3 (x^{4} x^{9}) y^{9} \cdot 6$

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$3 x^{4 + 9} y^{9} \cdot 6$

Add $4$ and $9$ .

$3 x^{13} y^{9} \cdot 6$

Multiply $6$ by $3$ .

$18 x^{13} y^{9}$