Question

How we can know that a number have a rational square root

Answer 1

by using for b^=√4ac

Answer 2

hey mate

Very-well-known proof by contradiction: if √n were rational, let √n = a/b, with a,b in lowest reduced form, hence have no common divisor. ... You can also take the square root of a rational non-integer, that is a fraction, and if the numerator and denominator are both perfect squares, you will have rational square roots.

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