What is the square root of (16/25)?

##4/5##

##16/25 = (4*4)/(5*5) = (4/5)*(4/5) = (4/5)^2##

So ##sqrt(16/25) = sqrt((4/5)^2) = 4/5##

##-4/5## is also a square root of ##16/25##, but by convention when we say the square root, we tend to mean the positive one.