Question

For which number can a zero be removed without changing the number's value?

Answer 1

So are you saying if we have f(x)=(x-3)(x+3) and g(x)=x-3
when is f(x) equal to g(x) if any such x number exists?

Answer 2

Try to solve (x-3)(x+3)=x-3
and see
I will give your first step: x^2-9=x-3