Math Is Fun Forum

4littlepiggiesmom

Member

Registered: 2006-01-09

Posts: 42

Find sum of 100 terms in a sequence?

My daughter had to miss math class for a music event and wants me to check her answers??? So here I am looking for help~

Find the sum of the first 100 terms of the aruthmetic sequence 19, 13 ,7,.....?  We came up with b

a. -58,100
b. -556
c. _27,800
d. -55,600
e. nnone of these

George,Y

Member

Registered: 2006-03-12

Posts: 1,379

Re: Find sum of 100 terms in a sequence?

c, and there is a little trick-- notice c is one half of d, and think what's in the examiner's mind to do so

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X'(y-Xβ)=0

4littlepiggiesmom

Member

Registered: 2006-01-09

Posts: 42

Re: Find sum of 100 terms in a sequence?

Thanks!

Jenilia

Member

Registered: 2005-07-09

Posts: 64

Re: Find sum of 100 terms in a sequence?

What is a aruthmetic sequence?

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Ideas are funny little things, they won't work unless you do.

Jai Ganesh

Administrator

Registered: 2005-06-28

Posts: 48,421

Re: Find sum of 100 terms in a sequence?

An Arithmetic Progression or sequence is such that the difference between any two successive terms of the series is the same. For example,
(1) 2, 5, 8, 11, 14, 17, ...
(2) 1, 5, 9, 14, 17, 21, .....
(3) 15, 13, 11, 9, 7, 5, 3, 1, ...
(4) 0.5, 2, 3.5, 5, 6.5, 8, 9.5 etc.
You can see that the difference between any two consecutive terms is always the same for the entire series. In example (1), it is 3, in (2) it is 4, in (3), it is -2 and in (4) it is 1.5.
The first erms of the Aritmetic Series or Progression is denoted by 'a' and the common difference by 'd'.
The nth term, tn is given by tn= a+(n-1)d and
the sum of n terms is given by
Sn= n/2[2a+(n-1)d]

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It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

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