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Question
Mathematics
The value of r for which 20Cr 20C0 + 20Cr-1 20C1 + 20Cr-2 20C2 + .... 20C0 20Cr is maximum, is
Q. The value of
r
for which
20
C
r
20
C
0
+
20
C
r
−
1
20
C
1
+
20
C
r
−
2
20
C
2
+
....
20
C
0
20
C
r
is maximum, is
3095
223
JEE Main
JEE Main 2019
Binomial Theorem
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A
20
67%
B
15
5%
C
11
8%
D
10
20%
Solution:
Given sum = coefficient of
x
r
in the expansion of
(
1
+
x
)
20
(
1
+
x
)
20
, which is equal to
40
C
r
It is maximum when
r
=
20