a^2 - 3b^2 = 0
or a^2 = 3b^2
a^2 + b^2 = 3b^2 + b^2 = 4b^2
sqrt(4b^2) = 2b
as we know b is an integer
so B is sufficient.
Also, A just tells us that a^2 is an integer so insufficient.
If b is an integer .... Please help
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Source: Beat The GMAT — Data Sufficiency |












