\[\frac{49}{5\sqrt{2} - 1\ } = \frac{49 \cdot \left( 5\sqrt{2} + 1 \right)}{\left( 5\sqrt{2} - 1 \right)\left( 5\sqrt{2} + 1 \right)} =\]
\[= \frac{49 \cdot \left( 5\sqrt{2} + 1 \right)}{25 \cdot 2 - 1} = \frac{49 \cdot \left( 5\sqrt{2} + 1 \right)}{49} =\]
\[= 5\sqrt{2} + 1\]