Let's look at each square root and what we can take out.
[tex]2 \sqrt{20} =2 \sqrt{2*2*5} =4 \sqrt{5} [/tex]
3 square root 7 can not be simplified, as well as 2 square root 5. But, we can change 4 square root 63.
[tex]4 \sqrt{63}=4 \sqrt{3*3*7}=12 \sqrt{7} [/tex]
Now, we have:
[tex]4 \sqrt{5}-3 \sqrt{7} -2 \sqrt{5} +12 \sqrt{7} [/tex]
We can now complete this problem:
[tex]2 \sqrt{5}+9 \sqrt{7} [/tex]
This is the same as the second answer, so that is the correct choice. Let me know if you need any more help!
