Question

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Answer 1

Substitute and sum it up.\[2(1) + 5 + 2(2) + 5 + 2(3) + 5\cdots2(8) +5\]

Answer 2

ok

Answer 3

the sum is 112?

Answer 4

Wait.\[5\cdot 8 + 2\sum_{k=1}^{8}k = 40 + 2\cdot36 = 40 + 72 \]

Answer 5

Yes sir.

Answer 6

and the expanded form is the : 2(1) + 5 and so on?

Answer 7

yes
replace k by 1, then by 2, then by 3 etc
put a plus sign between the terms

Answer 8

Expanded form:
2(1) + 5 + 2(2) + 5 + 2(3) + 5 + 2(4) + 5 + 2(5) + 5 + 2(6) + 5 + 2(7) + 5 + 2(8) + 5

Answer 9

yup

Answer 10

\[\rm \Large\sum_{blah var=1}^{somenumber}\large f(blahvar) = f(1) + f(2)\cdots f(somenumber)\]