Work Step by Step
From the text of the exercise $x^2-a\gt0\\(x-\sqrt a)(x+\sqrt a)\gt0$ Thus from what we leaned $-\sqrt a\gt x$ or $x\gt \sqrt a$. Thus we proved what we had to.
You can help us out by revising, improving and updating this answer.Update this answer
After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.