请问(根号6)-2与2-(根号2)如何比较大小?不用计算器.

问题描述:

请问(根号6)-2与2-(根号2)如何比较大小?不用计算器.

(√6+√2)^2
=8+2√12
=8+√48
(2+2)^2=16=8+√64
√6+√2√6-2

解(√6-2)-(2-√2)
=√6+√2-4
又由(√6+√2)^2
=8+2√12
=8+4√3
<8+4*2
=16
即(√6+√2)^2<16
即(√6+√2)<4
即√6+√2-4<0
即(√6-2)<(2-√2)

(根号6)-2
=(√6-2)(√6+2)/(√6+2)
=(6-4)/(√6+2)
=2/(√6+2)
2-√2
=2/(2+√2)
∵√6+2>2+√2>0
∴2/(√6+2)