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Calculate the sum:
[tex]\[ \sum_{n=1}^5 (2n + 1) \][/tex]

A. 35
B. 14
C. 11


Sagot :

Let's solve the given summation step-by-step:

The expression given is:

[tex]\[ \sum_{n=1}^5 (2n + 1) \][/tex]

This notation means we need to find the sum of \(2n + 1\) for \(n\) ranging from 1 to 5. Let's calculate what each term in the series is:

For \(n = 1\):
[tex]\[ 2(1) + 1 = 2 + 1 = 3 \][/tex]

For \(n = 2\):
[tex]\[ 2(2) + 1 = 4 + 1 = 5 \][/tex]

For \(n = 3\):
[tex]\[ 2(3) + 1 = 6 + 1 = 7 \][/tex]

For \(n = 4\):
[tex]\[ 2(4) + 1 = 8 + 1 = 9 \][/tex]

For \(n = 5\):
[tex]\[ 2(5) + 1 = 10 + 1 = 11 \][/tex]

Now, we add all these terms together:

[tex]\[ 3 + 5 + 7 + 9 + 11 \][/tex]

Let's sum these numbers step-by-step:

First, add 3 and 5:
[tex]\[ 3 + 5 = 8 \][/tex]

Next, add 8 and 7:
[tex]\[ 8 + 7 = 15 \][/tex]

Next, add 15 and 9:
[tex]\[ 15 + 9 = 24 \][/tex]

Finally, add 24 and 11:
[tex]\[ 24 + 11 = 35 \][/tex]

So the sum of the series from \(n = 1\) to \(n = 5\) for the expression \(2n + 1\) is:

[tex]\[ \sum_{n=1}^5 (2n + 1) = 35 \][/tex]