[tex] \sqrt{3} \ \textless \ 2 \sqrt{7} =\ \textgreater \ | \sqrt{3} -2 \sqrt{7} |=2 \sqrt{7} - \sqrt{3} \\ | \sqrt{3} +2 \sqrt{7} |=2 \sqrt{7}+ \sqrt{3} \\ \frac{ \sqrt{(2 \sqrt{7}- \sqrt{3})(2 \sqrt{7}+ \sqrt{3} ) } }{5} = \frac{ \sqrt{28-3} }{5}=1 [/tex]
1-1=0
[tex](a-b)(a+b)= a^{2}- b^{2} [/tex]
