(根号5+根号2-1)(5-根号10+根号5)
=√5(√5+√2-1)(√5-√2+1)
=√5×[√5+(√2-1)][√5-(√5-1)]
=√5×[(√5)²-(√2-1)²]
=√5×(5-2-1+2√2)
=√5×(2+2√2)
=2√5+2√10
(根号5+根号2-1)(5-根号10+根号5)
=√5(√5+√2-1)(√5-√2+1)
=√5×[√5+(√2-1)][√5-(√5-1)]
=√5×[(√5)²-(√2-1)²]
=√5×(5-2-1+2√2)
=√5×(2+2√2)
=2√5+2√10