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Byju's Answer
Standard XII
Mathematics
Complex Numbers
The value of ...
Question
The value of
∑
15
r
=
1
r
2
r
(
r
+
2
)
!
is equal to
A
(
17
)
!
−
2
16
(
17
)
!
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B
(
18
)
!
−
2
17
(
18
)
!
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C
(
16
)
!
−
2
15
(
16
)
!
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D
(
15
)
!
−
2
14
(
15
)
!
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Solution
The correct option is
A
(
17
)
!
−
2
16
(
17
)
!
∑
15
r
=
1
r
2
r
(
r
+
2
)
!
∑
15
r
=
1
(
r
+
2
−
2
)
2
r
(
r
+
2
)
!
∑
15
r
=
1
(
(
r
+
2
)
−
2
)
2
r
(
r
+
2
)
!
∑
15
r
=
1
(
r
+
2
)
2
r
−
2
r
+
1
(
r
+
2
)
!
∑
15
r
=
1
(
r
+
2
)
2
r
(
r
+
2
)
(
r
+
1
)
!
−
2
r
+
1
(
r
+
2
)
!
∑
15
r
=
1
2
r
(
r
+
1
)
!
−
2
r
+
1
(
r
+
2
)
!
Pluggin the values of r=1,2,3....
=
(
2
2
!
+
2
2
3
!
+
2
3
4
!
+
2
4
5
!
+
.
.
.
.
.
.
)
−
(
2
2
3
!
+
2
3
4
!
+
2
4
5
!
+
.
.
.
.
.
.
.
.
.
+
2
16
17
!
)
=
2
2
!
+
(
2
2
3
!
−
2
2
3
!
)
+
(
2
3
4
!
−
2
3
4
!
)
+
(
2
4
5
!
−
2
4
5
!
)
−
2
16
17
!
=
1
−
2
16
17
!
=
17
!
−
2
16
17
!
Suggest Corrections
1
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