Use the Product Rule to Multiply $$\sqrt [ 4 ] { 81 } \cdot \sqrt [ 4 ] { 256 }$$

Multiple Choice

Use the product rule to multiply. Assume all variables represent positive real numbers.
- $$\sqrt [ 4 ] { 81 } \cdot \sqrt [ 4 ] { 256 }$$

A) $- 1$
B) 7
C) $- 12$
D) 12