二次根式 如何比较大小

2025-03-30 17:36:55
推荐回答(3个)
回答1:

(根号8 + 根号 2 )的平方=10+2*根号16
(根号3 + 根号7 的大小)的平方=10+2*根号21
10+2*根号16<10+2*根号21
其他的同理

减法:
若(根号5 - 根号4)<(根号7 - 根号6)
则(根号5 - 根号4)-(根号7 - 根号6)<0
(根号5 - 根号4)-(根号7 - 根号6)=(根号5+根号6)-
(根号4+根号7)

(根号5+根号6)平方=11+2*根号30
(根号4+根号7)平方=11+2*根号28

so (根号5+根号6)-(根号4+根号7)>0

(根号5 - 根号4)>(根号7 - 根号6)

做这些题有啥用,高考又不考

回答2:

1.只要平方下:(根号8+根号2 )^2=10+2倍根号16
(根号3+根号7)^2=10+2倍根号21
因为2倍根号16<2倍根号21
所以10+2倍根号16<10+2倍根号21

2.一边乘
一边乘根号5+根号4,另一边乘根号7+根号6,得数都是1(根据平方差公式得)
因为根号5+根号4小于根号7+根号6,所以根号5-根号4大于根号7-根号6

回答3:

用计算器呗...

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