MathDB
Integral Points

Source: 1986 National High School Mathematics League, Exam Two, Problem 3

February 24, 2020
calculusintegration

Problem Statement

In rectangular coordinate system, define that if and only if both xx-axis and yy-axis of a point are integers, we call it integral point. Please color all intengral points in white, red and black, satisfying: (1) Points in every color appear on infinitely many lines that are parallel to xx-axis. (2) For any white point AA, red point BB, black point CC, we can find another red point DD, such that ABCDABCD is a parallelogram.