Well, in this case substituting k = x = h = 1
did happen to work, since
 






which is false.  So k=x=h=1 does produce
a counter-example.

However if the problem had been instead



and you substituted k = x = h = 1 







That would have been true, not false.  So you would
in that case need to use another number besides 1,
say 2, in order to get a counter-example.

For instance if you substituted k = x = h = 2 in



you get





which is false.

My point is that you may have to substitute other
values for x, h, and k besides 1 in order to find a 
counter-example.  Never assume that if you get a true 
equation, that the given equation is necessarily true.

In fact in some cases you cannot use the same value
for all the variables.  Take



If you use the same values for all three variables
you will never get a counter-example.

You'd have to use something like k=1, h=2, and k=3
to get a counter-example.

Edwin