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Mathematics
Mathematics
Problem
Find the sum of the arithmetic series
2
+
6
+
10
+
14
+
18
+
22
+
26
+
30
2 + 6 + 10 + 14 + 18 + 22 + 26 + 30
2
+
6
+
10
+
14
+
18
+
22
+
26
+
30
: a. by direct addition b. using
S
n
=
n
2
(
u
1
+
u
n
)
S_n = \frac{n}{2}(u_1 + u_n)
S
n
=
2
n
(
u
1
+
u
n
)
c. using
S
n
=
n
2
(
2
u
1
+
(
n
−
1
)
d
)
S_n = \frac{n}{2}(2u_1 + (n - 1)d)
S
n
=
2
n
(
2
u
1
+
(
n
−
1
)
d
)
.
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