根式计算:(1)(5+2根号6)(2根号6-5)(2)(根号20+根号5)÷根号5-根号三分之一×根号12
问题描述:
根式计算:(1)(5+2根号6)(2根号6-5)(2)(根号20+根号5)÷根号5-根号三分之一×根号12
答
(1)(5+2根号6)(2根号6-5)
=(2根号6)²-5²
=24-25
=-1
(2)(根号20+根号5)÷根号5-根号三分之一×根号12
=√20÷√5+√5÷√5-√(1/3×12)
=√4+1-√4
=2+1-2
=1