Question 491371
basically, you factor the 20 into factors that you can take the square root of.
square root of (20) is equivalent to square root of (4 * 5)
since you know that the square root of 4 is equal to 2, then you can remove the 4 from under the square root sign and make it a 2 outside the square root sign.
you get square root of (20) = 2 * square root of (5).


the principle involve is that the square root of (x^2) is equal to x.


replace x with 2 in this example and you get the square root of (2^2) is equal to 2


another principle involved is that the square root of (a * b) is equal to the square root of (a) times the square root of (b).


this allows you to take square root of (4 * t) and make it into square root of (4) times the square root of (5).


since you already know that the square root of (4) is equal to 2, then square root of (4) * square root of (5) becomes 2 * square root of (5).