If you do, it's false. Counterexample: n, x is 2, y is 1

2/(2-1) doesn't equal (2+1)/2

This is proof by what? So you only need one instance of a counterexample to prove it's false but you need to use variables to prove something is true. Well I found I found some numbers that made it true and I was going to use it to solve a problem but realized that it might not be true for all numbers and turns out it isn't.

]]>2/(2-1) doesn't equal (2+1)/2]]>

You only need one counter example to prove it is false. Try choosing some numbers for n, x and y.

Bob

]]>------

x - y

= or not =

n+y

------

x