Q8 of 53 Page 1

If a and b are two odd positive integers such that a > b, then prove that one of the two numbers and is odd and the other is even.

Given: a and b are two positive integers.


To prove: one of the two numbers and is odd and the other is even.


Proof:


Let the one number be 2p + 1


Let the other number be 2q + 1


As per question: p>q


As per first condition of the question:



As per second condition of the question:



Since adding two even numbers give an even number and adding two odd numbers gives an even number then the two numbers cannot both be even or both odd. Therefore, one must be odd and one even.


EXAMPLE:


Take a = 7 and b = 3 such that a>b


Now, = = 5 which is odd


And = = 2 which is even


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