How many pairs of integer solutions exist such that ?
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Suppose that m > 2 n − 1 .Then,
( 2 n − 1 ) 3 < 8 n 3 − 1 0 n 2 − n + 2 ⟺ 2 n 2 − 7 n + 3 > 0 ⟺ ( 2 n − 1 ) ( n − 3 ) > 0 ⟺ n < 2 1 , n > 3 .
Also suppose that m < 2 n . Then,
( 2 n ) 3 > 8 n 3 − 1 0 n 2 − n + 2 ⟺ 1 0 n 2 + n − 2 > 0 ⟺ ( 5 n − 2 ) ( 2 n + 1 ) > 0 ⟺ n < − 2 1 , n > 5 2 .
Therefore 2 n − 1 < m < 2 n and so m cannot be an integer; unless 2 1 ≤ n ≤ 3 and n < − 2 1 or n > 5 2 , which gives n = 1 , 2 , 3 , giving the pairs ( − 1 , 1 ) and ( 5 , 3 ) ( n = 2 does not give an integer solution).
The only other possibility is when n < 2 1 or n > 3 and − 2 1 ≤ n ≤ 5 2 , which gives only n = 0 which yields no integer solutions for m .
Thus the only pairs of solutions are ( − 1 , 1 ) and ( 5 , 3 ) .