- #1
Mr Davis 97
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I need to get something cleared up. Let's say we have the equation ##x = 1##. For this equation, the solution set is {1}. However, if I do the valid operation of multiplying both sides by x, we get ##x^2 = x##. Now the solution set is {0, 1}. Additionally, if I take the original equation and divide by x, I get ##\displaystyle 1 = \frac{1}{x}##. The solution set is still {1}, but now the domain of x values has changed, such that I can no longer try x = 0. My question is, how can we ever be sure of the solution set or the domain if they can change with doing operations with variables to both sides? An additional example is that we start with ##x^2 = x##. We think to divide both sides by x, since there is a common factor. However, doesn't this get rid of the solution x = 0? How would we ever know that ##x^2 = x## was our original equation, with the solution set {0, 1}?
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