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Three Absolute Value Trial (Posted on 2022-12-09) Difficulty: 3 of 5
M is any positive real number less than 2022.
Determine the total number of values of M for which the graphs of
y=abs(abs(abs(x-M)-x)-x) and y=x
intersect only at points with integer coordinates when graphed on the X-Y plane.

See The Solution Submitted by K Sengupta    
Rating: 3.5000 (2 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
re: Solution Comment 2 of 2 |
(In reply to Solution by Jer)

I agree with the answer of 505, but there are some errors in the solution.


abs(abs(abs(x-M)-x)-x) =x
if and only if 
M=-2x or M=4x or M=0 or M=2x

So for any positive M, x = 0 is not a solution (unless M = 0) 

For any positive M, the only solutions are x = M/4 and x=M/2.
In order for all solutions to be integers, M must be an integer multiple of 4.

There are 505 such positive M's which are <= 2022.

Bonus note:
For any negative M, the only solution is x = -M/2.
In order for all solutions to be integers, M must be an integer multiple of -2.

Edited on December 10, 2022, 10:50 am
  Posted by Steve Herman on 2022-12-09 15:41:46

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