Wednesday, 6 March 2019

calculus - How do I solve this indeterminate limit without the L'hospital rule?



I've been trying to solve this limit without L'Hospital's rule because I don't know how to use derivates yet. So I tried rationalizing the denominator and numerator but it didn't work.



lim



By the way, the answer is supposed to be \frac{2\sqrt{2}}{3}.


Answer



\lim_{x\to 4} \frac{\sqrt{2x+1}-3}{\sqrt{x-2}-\sqrt{2}} \\ = \lim_{x\to 4} \frac{2(x-4)(\sqrt{x-2}+\sqrt{2})}{(x-4)(\sqrt{2x+1}+3)} \\ = \lim_{x\to 4} \frac{2(\sqrt{x-2}+\sqrt{2})}{(\sqrt{2x+1}+3)} \\ = \frac{2\sqrt 2}{3}


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