Why is the square root of a perfect square always rational

A perfect square by defenition is a numer that is a result of squareing a whole number

so since y ou sqare root a perfect square, the square root and squared cancel and you are left with awhole number

ration numbers can be written in the form a/b where b is not equal zero so 5=5/1 and isi therefor rational
all whole numbers are rational numbers, so therefor all square roots of perfect squares are always rational
example
25=5^2 
square root of 25=5
rational