How do you find the partial sum of Σ(2n+5) from n=1 to 20?
Answers
Answered by
0
The partial sum formula for n terms looks like this:
∑
n
=
n
2
(
a
1
+
a
n
)
In words, it's the number of terms times the average of the first and last term.
In your case, with n=20, you need to find what
2
n
+
5
is for
n
=
1
and
n
=
20
.
When
n
=
1
,
2
n
+
5
=
7
.
Likewise, when
n
=
20
,
2
n
+
5
=
45
.
Your formula ends up looking like this:
(
20
2
)
(
7
+
45
)
=
520
.
Answered by
0
Answer:
sorry dear....................
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