Answer:
That is has root -12 meaning if you replace x with -12 you get 0.
Let p(x) = polynomial function.
Let g(x) = a factor of p(x).
g(x) = x + 12
Let g(x) be 0.
0 = x + 12
-12 = x
The binomial x + 12 tells us that -12 is the solution of p(x).
In other words, g(x) is a factor of p(x) because when x is -12, p(x) becomes 0.
