a)
[tex]|1- \sqrt{7} | \\ \sqrt{7} >1 =>1- \sqrt{7} <0=>|1- \sqrt{7} |=-(1- \sqrt{7} )=-1+ \sqrt{7} = \sqrt{7} -1 \\ |1- \sqrt{7} |=\sqrt{7} -1[/tex]
b)
[tex]\sqrt{3} - \sqrt{2} | \\ \sqrt{3} > \sqrt{2} => \sqrt{3} - \sqrt{2} >0=>| \sqrt{3} - \sqrt{2} |=\sqrt{3} - \sqrt{2} \\ | \sqrt{3} - \sqrt{2} |=\sqrt{3} - \sqrt{2}[/tex]
