Arithmetic Sequence

**xeronhart** · February 4th 2010, 09:33 PM

someone please help me to solve this..!

Find the minimum number of terms that must be taken from the sequence 3, 5, 7, 9...so that the sum is at least 440.

TQ..

**pickslides** · February 4th 2010, 09:38 PM

Your sequence is full of odd numbers therefore one is not the answer.

Let's try 2 numbers, I can see that 219 and 221 are in your sequence and add to the desired result. We are finished.

**CaptainBlack** · February 4th 2010, 10:56 PM

Originally Posted by xeronhart

someone please help me to solve this..!

Find the minimum number of terms that must be taken from the sequence 3, 5, 7, 9...so that the sum is at least 440.

TQ..

Check the wording of the problem to make sure it is not asking for how many consecutive terms of the sequence starting from the first is needed so that thier sum is at least 440

CB

**xeronhart** · February 4th 2010, 11:01 PM

find the minimum number of terms that must be taken from the sequence 3, 5, 7, 9,...so the sum is at least 440.

we are given this formula to solve the question..
s=n/2 [2a+(n-1)d]
where,
s=sum of the first n term,
n=number of term,
a=first term,

d=common difference.

the question ask to find the value of n..
some one out there please help me..

**VonNemo19** · February 4th 2010, 11:08 PM

Originally Posted by xeronhart

someone please help me to solve this..!

Find the minimum number of terms that must be taken from the sequence 3, 5, 7, 9...so that the sum is at least 440.

TQ..

You want

$\sum_{i=1}^n(2i+1)\geq440$

Or

$2\frac{n(n+1)}{2}+n\geq440$ .

Solve the inequality.

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