Find all $x$ numbers for $(x-1)(x-3) > 0$ I am learning calculus from Calculus by Michael Spivak and the exercise is to find all x numbers for $(x-1)(x-3) > 0$. Steps below are my procedure.


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*$(x-1)(x-3) > 0$

*$x^2-4x+3 > 0$

*$x^2 > 4x-3$

*$x > +-\sqrt{4x-3}$


I was wondering if I can say that $x > +-\sqrt{4x-3}$ is the answer.

Nope. You can't. Your solution $x > \sqrt {4x-3}$ does not convey anything. The question wants the set of real numbers for which this relation is valid.
Draw a number line and use this hint : Product of two positives or two negatives is positive and product of a positive and negative is negative!
