Jube
幼苗
共回答了16个问题采纳率:93.8% 举报
|
a -2
b | 2 =
a 2 -4
a •
b +4
b 2
∵
a •
b =0
∴ |
a -2
b | 2 =
a 2 -4
a •
b +4
b 2 =
a 2 +4
b 2
|
a +2
b | 2 =
a 2 +4
a •
b + 4
b 2
∵
a •
b =0
∴ |
a +2
b | 2 =
a 2 +4
a •
b + 4
b 2 =
a 2 +4
b 2
∴ |
a-2b
a+2b | =1
故选项为D
1年前
10