Determine The $x$ -Intercept(s) of the Quadratic Function $f ( x ) = x ^ { 2 } - 15 x + 56$

Multiple Choice

Determine the $x$ -intercept(s) of the quadratic function $f ( x ) = x ^ { 2 } - 15 x + 56$ .

A) $( 8,0 ) , ( 7,0 )$
B) $( - 4,0 ) , ( - 8,0 )$
C) $( - 8,0 ) , ( - 7,0 )$
D) $( 4,0 ) , ( 8,0 )$
E) no $x$ -intercept(s)