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Mathematics
Mathematics
Problem
A straight line is given by
r
=
(
1
+
t
)
i
+
3
t
j
+
(
1
−
t
)
k
r = (1+t)i + 3tj + (1-t)k
r
=
(
1
+
t
)
i
+
3
t
j
+
(
1
−
t
)
k
, where
t
∈
R
t \in \mathbb{R}
t
∈
R
. If this line lies in the plane
x
+
y
+
c
z
=
d
x + y + cz = d
x
+
y
+
cz
=
d
, then the value of
(
c
+
d
)
(c + d)
(
c
+
d
)
is a. -1 b. 1 c. 7 d. 9
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