[tex]3 \sqrt{-8} + 4 \sqrt{-50} [/tex]
[tex]= 3i \sqrt{8} + 4i \sqrt{50} [/tex]
[tex]= 3i \sqrt{4 \times 2} + 4i \sqrt{25 \times 2} [/tex]
[tex]= 6i \sqrt{2} + 20i \sqrt{2} [/tex]
[tex]= 26i \sqrt{2}[/tex]
I think part of the second question is cut off so I can't help but I hope I have helped with the first one.