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Mathematics
Mathematics
Problem
Evaluate
∑
r
=
0
5
(
7
r
)
\displaystyle \sum_{r=0}^{5}{7\choose r}
r
=
0
∑
5
(
r
7
)
. a)
121
121
121
b)
128
128
128
c)
120
120
120
d)
99
99
99
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