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help me in math

if i was asked to find the difference between two terms, should I write plus minus sth? instead of just one sigh?
Hi! I covered this topic a month ago on Youtube. The sign depends on sequence type: increasing or decreasing. For example:
Sequence is given like -2, 3, 8, 13 (increasing sequence)

Difference is d=5 because by def:
d=a2-a1= 3-(-2)=5. But in a case of decreasing sequence: 10, 7, 4, 1... you will have d=7-10=-3. I hope it is clear for
If you need a good source for Maths GCSE I can advise U MATH Science by Daniel Dallas on Youtube: Ive learnt there a lot with clear explanations and now Im doing Revision there. Btw, you can find sequence topic with lots of examples. Good luck
(edited 4 years ago)
thanks a lot for helping me,but I am in AS level now, is it also inclusive in the resourses?
the question I encountered is :in a geometric squence ,the common ratio is 2/5, the first term is 1953.125,find the difference between the sum of infinity and the sum of the first 10 terms of the series.
the mark scheme wrote:sum of infinity-sum of the first 10 terms=±0.341, should it be plus as the sum of infinity is greater?or the answer means it accept both signs?
Original post by Wuxinyu
thanks a lot for helping me,but I am in AS level now, is it also inclusive in the resourses?
the question I encountered is :in a geometric squence ,the common ratio is 2/5, the first term is 1953.125,find the difference between the sum of infinity and the sum of the first 10 terms of the series.
the mark scheme wrote:sum of infinity-sum of the first 10 terms=±0.341, should it be plus as the sum of infinity is greater?or the answer means it accept both signs?

It seems to me it is incorrect. Because if U use the formula S(inf)=U1/(1-r) U will get Sinf=1953.125/(3/5)=3255
Right now Daniel has a content for GCSE and other higher levels only, however if U ask him to create a video with explanation of the topic or the problem U couldnt do, he can do that. Im sure. It works for his Subscribers esp if you share and advise the channel to anyone who interested in MATHs. There was one of my friend who asked him to clarify an Oxford MAT 2019 and Daniel did it :smile: I was really amazed

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