To simplify
[tex]\sqrt[]{98}+\sqrt[]{8}[/tex]Now,
[tex]\begin{gathered} \sqrt[]{98}=\sqrt[]{49\times2} \\ =\sqrt[]{7^2\times2} \\ =7\sqrt[]{2} \end{gathered}[/tex]Again,
[tex]\begin{gathered} \sqrt[]{8}=\sqrt[]{4\times2} \\ =\sqrt[]{2^2\times2} \\ =2\sqrt[]{2} \end{gathered}[/tex]Then,
[tex]\begin{gathered} \sqrt[]{98}+\sqrt[]{8}=7\sqrt[]{2}+2\sqrt[]{2} \\ =9\sqrt[]{2} \end{gathered}[/tex]So, the simplified form is
[tex]7\sqrt[]{2}+2\sqrt[]{2}=9\sqrt[]{2}[/tex]