**I do not understand this**

You first write down the radiant ( the number under radical ) as product of its prime facors.

Fundamental law of Arithmetic says that : Every Composite number consists of product of its prime factors:

4 = 2. 2 = 2

^{2} 6 = 2 . 3

8 = 2.2 2 = 8

10 = 2 . 5

12 = 2 . 2 .3 = 2

^{2}. 3 14 = 2 . 7

16 = 2

^{4} 18 = 2 . 3

^{2} 20 = 2

^{2}. 5 We can multiply and divide the radicals, where the product and quotient to be a radical with product and quotient to be the product and quotient of the radicants of radicants .

√a . √b = √(ab) , √a / √b = √(a/b) .

To simplify: √(a

^{2}b ) = √a^{2}. √b = a √b So To Simplify:

√12 = √( 2

^{2}. 3 = 2 √3 √18 = √( 2 . 3

^{2}) = 3√2 √(20) = √( 2

^{2}. 5 ) = 2 √5 √24 = √(2

^{2}. 6 ) = 2 √6 √28 = √2

^{2}.7 = 2 √7