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Mathematics
Mathematics
Problem
Let
a
=
(
2
,
k
,
−
1
)
\mathbf a=(2,k,-1)
a
=
(
2
,
k
,
−
1
)
and
b
=
(
3
,
1
,
4
)
\mathbf b=(3,1,4)
b
=
(
3
,
1
,
4
)
. If the
i
^
\hat{i}
i
^
-component of
a
×
b
\mathbf a\times\mathbf b
a
×
b
is
9
9
9
, the value of
k
k
k
is a)
−
5
2
-\dfrac{5}{2}
−
2
5
b)
5
2
\dfrac{5}{2}
2
5
c)
2
2
2
d)
−
2
-2
−
2
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