How do you simplify #21sqrt8-2sqrt12+2sqrt18#?
I find it easier to split each number under the square root into its factors. Example: 8=2 x 2 x 2. However, in a square root, if one can cancel out two numbers, do so. in this case, there are three 2's. so, we can cancel out each of the twos, except the third, as it doesn't have a fourth 2 to cancel out with.