Question

Help me find answer combing and simply

Answer 1

$\sqrt{128}-3\sqrt{8}=\sqrt{64\cdot2}-3\sqrt{4\cdot2}=\sqrt{64}\cdot\sqrt{2}-3\cdot\sqrt{4}\cdot\sqrt{2}=\\\\ 8\sqrt{2}-3\cdot2\sqrt{2}=8\sqrt{2}-6\sqrt{2}=(8-6)\sqrt{2}=\boxed{2\sqrt{2}}$

Answer 2

Julie, as a friend I need to tell you that your spelling needs work.  Combine and simplify are very different from "combing" and "simply."

sqrt(128)=?  Look for perfect square factors of 128.   16 is such a factor; if we take 16 as one factor, the other one is 8.

Then sqrt(128) = sqrt(16)sqrt(8) = 4sqrt(8).  Subtract 3sqrt(8) from that and you get 1sqrt(8) (answer).