You have to find two factors of 75 that multiply together to get 75, and one must be a perfect square product.
So, when you divide 75 by 3, you get 25 which is the product of the perfect square, 5x5. Then you take that square root of 25 and get 5.
Then you put the other factor, 3, inside the radical and put the 5 outside the radical.
You have 5√3.
