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$\begingroup$

$$\left(\frac{1}{\sqrt a + \sqrt {a+1}} + \frac{1}{\sqrt a - \sqrt {a-1}}\right):\left(1+\frac{\sqrt{a+1}}{\sqrt{a-1}} \right)$$

I have tried simplifying the denominators, with no success. I was thinking about doing it the hard way and just multiplying both terms in the first parenthesis to get a common denominator, but I was wondering if there is an easier way to solve this.

  • 0
    Does the "$:$" denote division? – 2017-01-13
  • 0
    yes, the : symbol is division. – 2017-01-13

1 Answers 1

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$\displaystyle \frac{1}{\sqrt{a} + \sqrt{a+1}} + \frac{1}{\sqrt{a}-\sqrt{a-1}} = \sqrt{a+1}-\sqrt{a} + \sqrt{a} +\sqrt{a-1}=\sqrt{a+1} + \sqrt{a-1}$, so $\displaystyle (\sqrt{a+1} + \sqrt{a-1})\cdot\frac{\sqrt{a-1}}{\sqrt{a+1} + \sqrt{a-1}} = \sqrt{a-1}$