Year 12s: what will be the first way you research your future options? >>

Year 12s: what will be the first way you research your future options? >>

Year 12s: what will be the first way you research your future options? >>

C2 - Sum of series.. Need guidance!

Alright, so I can't use LaTex on this yet so I'll try type this the best I can.

I have a question, it says that the formula for the nth term is 12(0.5)^n -3. Then, it gives in sigma notation, show that the sum of the terms from 1 to 20 is -48. Could someone show me how to find the sum of this? I'm having a mind blank.

You can split the summation into two:

\displaystyle \sum_{n=1}^{20} \left(12(0.5)^n - 3\right) = \sum_{n=1}^{20} 12(0.5)^n - \sum_{n=1}^{20} 3

Does that help you?

(edited 11 years ago)

OP

Original post by notnek

You can split the summation into two:

\displaystyle \sum_{n=1}^{20} \left(12(0.5)^n - 3\right) = \sum_{n=1}^{20} 12(0.5)^n - \sum_{n=1}^{20} 3

Does that help you?

Yes I figured that out after a few attempts haha, thanks!

Quick Reply

Latest

Trending

Trending

Articles for you

How to revise for A-level Environmental Science exams: AQA explains what to do

How to revise for A-level Environmental Science exams: AQA explains what to do

Expert tips for revising A-level and Btec law

Expert tips for revising A-level and Btec law

How to revise for A-level Physics exams: AQA explains what to do

How to revise for A-level Physics exams: AQA explains what to do

What is an LLM and how could it benefit your career?

What is an LLM and how could it benefit your career?