Use Descartes' Rule of Signs and the Rational Zeros Theorem $$f ( x ) = x ^ { 4 } - 15 x ^ { 2 } - 16$$

Multiple Choice

Use Descartes' Rule of Signs and the Rational Zeros Theorem to find all the real zeros of the polynomial function. Use the
zeros to factor f over the real numbers.
- $$f ( x ) = x ^ { 4 } - 15 x ^ { 2 } - 16$$

A) $- 4,4 ; f ( x ) = ( x - 4 ) ( x + 4 ) \left( x ^ { 2 } + 1 \right)$
B) $4 ; f ( x ) = ( x - 4 ) ^ { 2 } \left( x ^ { 2 } + 1 \right)$
C) $- 1,1 ; f ( x ) = ( x - 1 ) ( x + 1 ) \left( x ^ { 2 } + 16 \right)$
D) $- 4 , - 1,4,1 ; f ( x ) = ( x - 4 ) ( x + 4 ) ( x - 1 ) ( x + 1 )$