Write the following two sequences using summation notation:
5 - 10 + 15 - 20 + 25 - 40
5 - 10 + 15 - 20 + 25 -
(hint: these are different)

Step-by-step explanation:

Sequence 1:

This is a finite sequence ending with 40

5-10+15-20+...40

= 5(1-2+3-4+5-6+7-8) (by taking 5 as common factor)

This is an alternating series with even numbers in the series having negative sign

Hence can be written as

This gives the I sequence in the summation notation.  Since there are only 8 terms n can take values as 1 to 8, with odd terms positive.

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Sequence 2:

This is the same as the previous sequence but with end point as infinite

This is an infinite series. Hence n can vary from 1 to infinity.

Thus sum would be

(Note that only the ending number is difference for both.)

answer: i think it is (1,-2)

it will cost dollar $540

the living room is 3 which means if we divide 325/3 then we get $108

therefore if 1part of the living room cost $108 and 3 costed $325

then total 5part of the room will cost 5*108 which gives $540