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Root Ratio Crossed Rational Resolution (Posted on 2023-02-22) Difficulty: 3 of 5
Determine all possible positive integers m such that:
          √(4m - 7)
         ...........
          √(m + 1)
is a rational number.

Provide adequate reasoning for your answer.

See The Solution Submitted by K Sengupta    
Rating: 4.0000 (2 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Some Thoughts Computer solution without analytical proof | Comment 1 of 3
The only value I found was m = 8,
with the ratio being sqrt(25)/sqrt(9) or 5/3

def isSquare(n):
    """ Input an integer, Returns True iff it is a perfect square. """
    if round(n**0.5)**2 == n:
        return True
    else:
        return False
    
big = 1000000
for m in range(2,big):
    num = (4*m - 7)**.5
    den = (m + 1)**.5
    if isSquare(4*m - 7) and isSquare(m + 1):
        print(m, int(num) , int(den))

  Posted by Larry on 2023-02-22 12:58:10
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