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Multivariable Calculus

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Difficult

Integer Coordinates

MVCALC-HKVLES

We wish to randomly select points from the same plane so that both of their coordinates are integers.

At least how many such points should we choose if we want to be sure that there will be two points among the chosen ones so that the midpoint of their line segment also has two integer coordinates?

A

Two

B

Three

C

Four

D

Five

E

Six