Answer:
8 - [tex]\sqrt{2}[/tex]
Or the decimal version 6.58578643
Step-by-step explanation:
[tex]\bf 4\sqrt{4}-4\sqrt{8}+\sqrt{98}~~\begin{cases}4=2\cdot 2\\\qquad 2^2\\8=2\cdot 2\cdot 2\\\qquad 2^2\cdot 2\\98=2\cdot 7\cdot 7\\\qquad 2\cdot 7^2\end{cases}\implies 4\sqrt{2^2}-4\sqrt{2^2\cdot 2}+\sqrt{2\cdot 7^2}\\\\\\(4\cdot 2)-(4\cdot 2)\sqrt{2}+7\sqrt{2}\implies 8\stackrel{like-terms}{-8\sqrt{2}+7\sqrt{2}}\implies 8-\sqrt{2}[/tex]
