How to determine a perfect square in ruby?

Question

ruby

A perfect square is an integer whose square root is an integer.
This is how I check if a number is a Fibonacci number:

def perf_square x
   return x == Math.sqrt(x) ** 2
end
perf_square(5 * (num ** 2) + 4) || perf_square(5 * (num ** 2) - 4) ? "IsFibo" : "IsNotFibo"

When the number num is small, there are no problems, but with large numbers, the square does not pass the test for "ideality".
Is it possible to solve the problem of finding a perfect square in ruby? If so, in which direction to dig?

Answer 1

def perf_square x
  Math.sqrt(x).to_r.denominator == 1
end

Answer 2

def is_perf_quare x
    return Math.sqrt(x).is_a? Integer
end

Not?