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A simple equation (Posted on 2018-06-24) Difficulty: 2 of 5
Solve (pen and paper only):

5*3x+4=y2

List all possible integer solutions.

No Solution Yet Submitted by Ady TZIDON    
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No Subject | Comment 1 of 3
a few very small steps: 
clearly x is not negative else the LHS is not integer.
x = 0 and y= +/- 3 is a solution.
for all y that work, so does -y, as LHS is positive
x are even, since this produces LHS numbers ending in ..09 and ...49
(x odd makes numbers ending in 19 and 39 which can not be squares)
likewise y ends in 3 or 7
I wonder how 5*3^x=(y-2)(y+2) might help



Edited on October 10, 2018, 5:24 pm
  Posted by Steven Lord on 2018-06-24 15:11:46

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