Problem: Prove that the equation x2006−4y2006−2006=4y2007+2007y has no solution in the set of the positive integers.
Solution
Solution: We assume the contrary is true. So there are x and y that satisfy the equation. Hence we have x2006=4y2007+4y2006+2007y+2006x2006+1=4y2006(y+1)+2007(y+1)x2006+1=(4y2006+2007)(y+1) But 4y2006+2007≡3(mod4), so x2006+1 will have at least one prime divisor of the type 4k+3. It is known (and easily obtainable by using Fermat's Little Theorem) that this is impossible.
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