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Mathematics
Mathematics
Problem
If the planes
x
+
2
y
+
k
z
=
0
x + 2y + kz = 0
x
+
2
y
+
k
z
=
0
and
2
x
+
y
−
2
z
=
0
2x + y - 2z = 0
2
x
+
y
−
2
z
=
0
are at right angles, then the value of
k
k
k
is
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