Simplify Write the Answer in Exponential Form Without Negative Exponents $x ^ { - 9 / 2 }$

Multiple Choice

Simplify. Write the answer in exponential form without negative exponents.
- $x ^ { - 9 / 2 }$

A) $- x ^ { 9 / 2 }$
B) $\frac { - 1 } { x ^ { 9 / 2 } }$
C) $\frac { 1 } { \mathrm { x } ^ { 2 / 9 } }$
D) $\frac { 1 } { x ^ { 9 / 2 } }$