3n⁴· 6n⁹=  3 · n⁴ · 6 · n⁹

= 3 · 6 · n⁴ · n⁹         (Apply commutative property of multiplication: a × b = b × a)

Since base is common,apply the product of powers property: a^m·aⁿ= a^{m + n}.

= 3 · 6 · n^{4 + 9}

= 3 · 6 · n¹³              (Add exponents: 4 + 9 = 13)

= 18n¹³                     (Multiply: 3 × 6 =  18)

The product of  3n⁴· 6n⁹ is 18n¹³.