Answer:
499
Step-by-step explanation:
9,999 would be the greatest value
9500 would be the smallest value
if you subtract them you'll get 499
f(x)= -3x² - 12x - 5
-3(x+2)² + 7
-3(x+2)(x+2) + 7
(-3x-6)(x+2) + 7
-3x² - 6x - 6x - 12 + 7
-3x² - 12x - 5
$749 each