Question

Find a counterexample to show that the given conjecture is false:

The sum of two positive even integers is always an odd integer.

Answer 1

20 + 16 = 36

Explanation:

The conjecture: "The sum of two positive even integers is always an odd integer" can be easily be proven false with a counterexample.

Pick A=20 and B=16, both are positive even integers.

The sum of both A + B = 36 is an even integer. This is a counterexample because being even is the contrary of being odd.

Counterexample: 20 + 16 = 36

In fact, the conjecture is always false, since there cannot be found any pair of positive integers whose sum is odd.

Other possible counterexamples are:

10 + 8, 700 + 40, 12 + 14, etc.