Discrete math homework:
which one of the following would disprove the conjecture that the sum of two irrational numbers is irrational?
a) the fact that ? + 2, which is the sum of ? and 2, is irrational.
b) the fact that each of ? + 2 and 5 - ? is an irrational number and that their sum is 7.
c) the fact that each of 2 ? - 2 and 2 - ? is an irrational number and that their sum is ? .
d) none of the above
***the answer is (b). i just don't understand how.**