[tex]| \sqrt{1} - \sqrt{2} | + | \sqrt{2} - \sqrt{3} |+| \sqrt{3} - \sqrt{4} |+...+| \sqrt{47} - \sqrt{48} |+| \sqrt{48} - \sqrt{49} | \\ = \sqrt{2} - \sqrt{1}+ \sqrt{3} - \sqrt{2}+ \sqrt{4} - \sqrt{3}+...+ \sqrt{48} - \sqrt{47}+ \sqrt{49} - \sqrt{48}= \\ =-\sqrt{1} + \sqrt{49}=-1+7=\boxed{6}[/tex]