Question 486918
Hint: set the denominator to be zero to find the restricted values.

For your problem:
(x + 3)(x - 1) = 0
x + 3 =0 or x - 1 = 0
x = -3 or x = 1

Then the domain is all real numbers except -3 and 1

D = {x| x is not equal to -3 or 1}