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Mathematics
Mathematics
Problem
9. Find
∣
x
⃗
∣
|\vec{x}|
∣
x
∣
, if for a unit vector
a
⃗
,
(
x
⃗
−
a
⃗
)
⋅
(
x
⃗
+
a
⃗
)
=
12
\vec{a},(\vec{x}-\vec{a}) \cdot(\vec{x}+\vec{a})=12
a
,
(
x
−
a
)
⋅
(
x
+
a
)
=
12
.
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