Do there exist four consecutive positive integers whose product is a perfect square?
Solution
Solution:
The answer is no. If x≥1 is an integer, x(x+1)(x+2)(x+3)=[x(x+3)]⋅[(x+1)(x+2)]=[x2+3x]⋅[x2+3x+2]=[(x2+3x+1)−1]⋅[(x2+3x+1)+1]=(x2+3x+1)2−1. Therefore the product of four consecutive positive integers is always one less than a square, and therefore cannot be a square since two positive squares cannot differ by 1.
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Source: MathNet,
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