Hello, Prof Paulo!
I don't trust the wording of this problem.
Besides, the solution is too simple.
The following figure is composed of 17 matches to form 6 squares geometrically similar to each other. Redundant . . . all squares are geometrically similar. Code:
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There are eight squares which are geometrically similar:
. . six 1-by-1 squares,
. . two 2-by-2 squares.
Remove only 3 matches in order to get only 4 squares geometrically similar to each other. Solution:
Code:
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Perhaps the author meant congruent squares?