Evaluate the summation of 2 n plus 5, from n equals 1 to 12.
Solution:
Given, the expression is 2 n plus 5.
We have to find the summation of 2 n plus 5, from n equals 1 to 12.
Summation of 2 n plus 5 can be written as \(\sum_{n=1}^{12}2n+5\)
= 2(1) + 5 + 2(2) + 5 + 2(3) + 5………………….+ 2(12) + 5
= 2 + 5 + 4 + 5 + 6 + 5………………….+ 24 + 5
= [2 + 4 + 6 + ……… + 24] + 12(5)
= [2 + 4 + 6 + ……… + 24] + 60
[2+ 4 + 6 + ……… + 24] represents arithmetic progression.
The sum of an arithmetic progression is given by
S = n/2 [2a + (n - 1)d]
Where, a is the first term
d is the common difference
Here, a = 2, n = 12
Common difference, d = 4 -2 = 6 - 4 = 2
S = 12/2 [2(2) + (12 - 1)(2)]
= 6[4 + 11(2)]
= 6[4 + 22]
= 6(26)
[2 + 4 + 6 + ……… + 24] = 156
Now, [2 + 4 + 6 + ……… + 24] + 60 = 156 + 60
= 216
Therefore, the required value is 216.
Evaluate the summation of 2 n plus 5, from n equals 1 to 12.
Summary:
The summation of 2 n plus 5, from n equals 1 to 12 is 216.
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