Use Factoring and the Root Method to Solve the Polynomial $$x ^ { 4 } - 6 x ^ { 2 } + 9 = 0$$

Multiple Choice

Use factoring and the root method to solve the polynomial equation.
- $$x ^ { 4 } - 6 x ^ { 2 } + 9 = 0$$

A) 3
B) $- 3,3$
C) $\sqrt { 3 }$
D) $- \sqrt { 3 } , \sqrt { 3 }$