First you factor 128 to get two numbers (one has to be a perfect square)[tex]2\sqrt{128} = 2\sqrt{64 * 2}[/tex]
You can then break them down into separate square roots like so
[tex]2\sqrt{64 * 2} = 2\sqrt{64}\sqrt{2}[/tex]
Then you simplify the root of 64
[tex]2\sqrt{64}\sqrt{2} = 2 * 8\sqrt{2}[/tex]
And finally, multiply the 2 by the 8 and you have your final answer
[tex]16\sqrt{2}[/tex]
