QUESTION IMAGE
Question
evaluate each series described.
- \\(\sum_{m = 1}^{6} (10m - 3)\\)
- \\(\sum_{n = 1}^{7} (14 - 4n)\\)
- \\(\sum_{k = 1}^{10} 4^{k - 1}\\)
- \\(\sum_{i = 1}^{8} (-6)^{i - 1}\\)
given the recursive formula for the sequence, find the first five terms.
- \\(a_n = a_{n - 1} + 9\\), \\(a_1 = 16\\)
- \\(a_n = a_{n - 1} + 8\\), \\(a_1 = -28\\)
- \\(a_n = a_{n - 1} - 2\\), \\(a_1 = -30\\)
- \\(a_n = a_{n - 1} - 6\\), \\(a_1 = 39\\)
- \\(a_n = a_{n - 1} \cdot 5\\), \\(a_1 = 2\\)
- \\(a_n = a_{n - 1} \cdot -2\\), \\(a_1 = 3\\)
- \\(a_n = a_{n - 1} \cdot 4\\), \\(a_1 = -2\\)
- \\(a_n = a_{n - 1} \cdot -5\\), \\(a_1 = 2\\)
Let's solve problem 9: $\sum_{m = 1}^{6}(10m - 3)$
Step 1: Expand the summation
We need to find the sum of the series by substituting $m = 1, 2, 3, 4, 5, 6$ into the expression $10m - 3$ and then adding them up.
For $m = 1$: $10(1) - 3 = 10 - 3 = 7$
For $m = 2$: $10(2) - 3 = 20 - 3 = 17$
For $m = 3$: $10(3) - 3 = 30 - 3 = 27$
For $m = 4$: $10(4) - 3 = 40 - 3 = 37$
For $m = 5$: $10(5) - 3 = 50 - 3 = 47$
For $m = 6$: $10(6) - 3 = 60 - 3 = 57$
Step 2: Sum the terms
Now we add all these terms together: $7 + 17 + 27 + 37 + 47 + 57$
We can use the formula for the sum of an arithmetic series $S_n=\frac{n(a_1 + a_n)}{2}$, where $n = 6$ (number of terms), $a_1 = 7$ (first term), and $a_n = 57$ (last term).
$S_6=\frac{6(7 + 57)}{2}=\frac{6\times64}{2}= 3\times64 = 192$
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