问题:
设向量
a
,
b
满足|
a
|=1,|
a
-
b
|=
3
,
a
•(
a
-
b
)=0,则|2
a
+
b
|=______.
设向量
,
满足|
|=1,|
-
|=
,
•(
-
)=0,则|2
+
|=______.
a |
b |
a |
a |
b |
3 |
a |
a |
b |
a |
b |
参考答案: