Find All Real Solutions of the Polynomial Equation $x ^ { 4 } - 8 x ^ { 3 } + 56 x - 49 = 0$

Multiple Choice

Find all real solutions of the polynomial equation $x ^ { 4 } - 8 x ^ { 3 } + 56 x - 49 = 0$ .

A) $x = 1,7 , \pm \sqrt { 7 }$
B) $x = 1,49$
C) $x = 1 , - 8 , - 7$
D) $x = 1 , - 49,14$
E) $x = 1 , \pm \sqrt { 7 }$