(This is for practice purposes only; to make the computations a little less messy, the root will turn out to be an integer, so one could use the Rational Zero test instead.)
We want to find a real root of
We set y=s-t, where
The first equation yields
Substituting this into (2) yields
which can be rewritten as
The quadratic formula tells us that
We discard one of the solution to obtain
Consequently
so our solution is
Substituting back for x, we see that
What a complicated way of writing x=3!
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Helmut Knaust