√7>√5 √8>√6
√7+√8>√5+√6
1/(√7+√8)-1/(√5+√6)
(√7-√8)(√7+√8)/(√7+√8)>(√5-√6)(√5+√6)/(√5+√6)
√7-√8>√5-√6
√7-2√2>√5-√6
√6+√7>2√2+√5