问题:
已知
a
=(2,-3),
b
=(1,m)(m∈R),
c
=(2,5)
(I)若 (
a
+
b
)•
c
=1,求m的值;(II)若 (
a
-
b
)•(
b
+
c
)>0,求m的取值范围.
已知
=(2,-3),
=(1,m)(m∈R),
=(2,5)
(I)若 (
+
)•
=1,求m的值;(II)若 (
-
)•(
+
)>0,求m的取值范围.
a |
b |
c |
(I)若 (
a |
b |
c |
a |
b |
b |
c |
参考答案: