What is the domain function f (x)= ×-5 over x^2- 9
a. all real number but 9
b. all real numbers but 3 and -3
c. all positive real numbers
d. all real numbers but 5 and 9

Assuming your function looks like this: (x-5)/(x^2 - 9), the numbers that are not "allowed" are the ones that cause the denominator to equal 0.  That would be a 3 and a -3, because when you square a 3 and a -3, your result is a 9, and putting a 9 in there makes that denominator 0.  So your answer is b

40%=2/550=1/230=3/1056=14/25