Question 563024
For #1-3, review what natural numbers, rational numbers, integers, etc. are defined as.


For #4, x^0 = 1 because x^(a-b) = (x^a)(x^b), so if a = b, x^0 = (x^a)/(x^a) = 1 (assume x is not 0).


For #5, 5/0 is undefined because we cannot divide 5 into groups of zero.