Solve the Problem $f ( x ) = x ^ { 2 } - x - 56$

Multiple Choice

Solve the problem.
-Let $f ( x ) = x ^ { 2 } - x - 56$ . Find all values $x$ for which $f ( x ) = 0$ .

A) 1,56
B) $- 7 , - 8$
C) 7,8
D) $- 7,8$