Bluebook试题3 · 第 21 题

Function f is defined by f(x)= (x + 6)(x + 5)(x + 1). Function g is defined by g(x)= f(x - 1). The graph of y = g(x) in the xy-plane has x-intercepts at (a, 0), (b, 0), and (c, 0), where a, b, and c are distinct constants. What is the value of a + b + c?