Chapter 10 - Radical Expressions and Equations - 10-2 Simplifying Radicals - Practice and Problem-Solving Exercises - Page 610: 24

240

We first combine this into one square root: $4 \times 2 \sqrt {10\times 90} = 8 \sqrt {900}$ We see if any of the factors of a radical are perfect squares (meaning that their square root will be an integer) to see if the radical is in its most simplified form. We see that 900 is a perfect square, so we know that we can simplify: $8 \sqrt {900}=8 \times 30=240$