Yes. The square root of 25 is 5, which is a real number.
no. is not a real number
the square root of 25 is 5
The square root of 8 over 25 is irrational, and real.
The square root of 25 is 5. 5 is a rational number. A rational number is a whole integer, like 3 or 5 or -8. Also, 4.333333... is a rational number because we know exactly what the number is. We know the number is 4 and 1/3, nothing more, nothing less. An irrational number is a number that goes on and on, with no specific pattern. A famous irrational number is pi. 3.14159....... Another example would be 453.788192742917471085723.......... Or 2.10100100010000100000........
If by "radical" you mean "square root of", then yes. Both square roots of 25 are real numbers.
Because the square root of -25 would be that number that, squared, would equal -25. No number, positive or negative, can result in a negative square. Since -25 is a negative number, no number, positive or negative, can be squared to equal -25.
The principal root of a number is the positive real square root of the number - if it exists. Since -25 is negative, it does not have a real square root. Its square roots are the imaginary numbers +/-5i where i is the [imaginary] square root of -1. i is neither positive nor negative and so neither +5i nor -5i is a principal root.
The square root of 25 is 5 ... rational.
Any odd root, for example the cube root, of -3.24 is a real number.
Of course, not only can it be a real number but it is a real number. When you take the square root times itself, the result is a number that is real.