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Mathematics
Problem
Which of the following expressions represents the sum
1
+
2
+
3
+
⋯
+
n
1 + 2 + 3 + \dots + n
1
+
2
+
3
+
⋯
+
n
in terms of
n
n
n
? a)
n
(
n
+
1
)
n(n+1)
n
(
n
+
1
)
b)
n
(
n
−
1
)
2
\dfrac{n(n-1)}{2}
2
n
(
n
−
1
)
c)
n
(
n
+
1
)
2
\dfrac{n(n+1)}{2}
2
n
(
n
+
1
)
d)
n
2
2
\dfrac{n^{2}}{2}
2
n
2
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