问题 填空题
已知|
a
|=2,|
b
|=5,
a
b
=-3,则|
a
-
b
|=______.
答案

∵|

a
|=2,|
b
|=5,
a
b
=-3

|

a
-
b
|2

=

a
2+
b
2-2
a
b

=4+25-2×(-3)

=35

∴|

a
-
b
|=
35

故答案为:

35

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