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Mathematics
Problem
Find a simplified expression in terms of
n
n
n
for
∑
k
=
1
n
(
3
k
+
2
)
−
∑
k
=
1
n
(
k
−
1
)
\displaystyle \sum_{k=1}^{n} (3k+2)\; - \; \sum_{k=1}^{n} (k-1)
k
=
1
∑
n
(
3
k
+
2
)
−
k
=
1
∑
n
(
k
−
1
)
. a)
2
n
2
+
8
n
2n^{2}+8n
2
n
2
+
8
n
b)
n
2
+
3
n
n^{2}+3n
n
2
+
3
n
c)
n
2
+
4
n
n^{2}+4n
n
2
+
4
n
d)
2
n
2
+
3
n
2n^{2}+3n
2
n
2
+
3
n
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