Perfect square??

4n+2=2(2n+1)

when n is a natural number, 2n+1 has to be an odd number and 4n+2 has to be an even number

the prime factors of 4n+2

 are 2 and the prime factors of 2n+1

since 2n+1 is an odd number, all its factors will be odd numbers

so

when you take the square root of the given number,,whether the odd number is a perfect square or not , 2 will be having irrational square root which makes the square root  of the given number as an irrational number and  not a real number.