Сократить дробь: [latex]1) \frac{ \sqrt{x} -1}{x-1} \\ \\ 4) \frac{17- \sqrt{17}}{\sqrt{17}} \\ \\ 6) \frac{\sqrt{21}-3}{7- \sqrt{21}} [/latex]

1) =[latex] \frac{ \sqrt{x} -1}{( \sqrt{x} -1)( \sqrt{x} +1)} = \frac{1}{ \sqrt{x} +1} [/latex] 4) =[latex] \frac{ \sqrt{17}( \sqrt{17}-1) }{ \sqrt{17} } = \sqrt{17} -1[/latex] [latex] \frac{ \sqrt{3} \sqrt{7} - \sqrt{3} \sqrt{x} 3}{ \sqrt{7} \sqrt{7} - \sqrt{7} \sqrt{3} } = \frac{ \sqrt{3} ( \sqrt{7}- \sqrt{3}) }{ \sqrt{7}( \sqrt{7} - \sqrt{3}) } = \frac{ \sqrt{3} }{ \sqrt{7} } [/latex]