SOLUTION: help me solve this question {{{ sqrt ( (3n-5)/(n+1) )}}} is an integer

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Question 600971: help me solve this question
++sqrt+%28+%283n-5%29%2F%28n%2B1%29+%29 is an integer

Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
++sqrt+%28+%283n-5%29%2F%28n%2B1%29+%29

In order for that to equal to an integer,
what's under the radical must be a perfect square. 

We compare the fraction %283n-5%29%2F%28n%2B1%29 to the fraction

3n%2Fn, and observe that %283n-5%29%2F%28n%2B1%29 has a smaller 
numerator and a larger denominator than 3n%2Fn%7D%7D+so+it%27s+less+%0D%0Athan+%7B%7B%7B3n%2Fn which is 3. So ++%283n-5%29%2F%28n%2B1+%29 is a perfect
square less than 3. 

The only perfect square less than 3 is 1, so what's under the 
radical must equal to 1.  So

+%283n-5%29%2F%28n%2B1%29+ = 1

Multiply both sides by n+1

3n - 5 = n + 1
    2n = 6
     n = 3

So n=3 and therefore

++sqrt+%28+%283n-5%29%2F%28n%2B1%29+%29 = ++sqrt+%28+%283%283%29-5%29%2F%28%283%29%2B1%29+%29 = ++sqrt+%28+%289-5%29%2F%283%2B1%29+%29 = 4%2F4 = 1

Edwin