Nth term

[wolfson]

Relating to the e-mail I received:

 

Could you please help me find the nth term for this sequence:

 

1,3,5,7,9,11,

 

The nth term is 2n + 1

 

 

N= 0 1 2 1 3 5

 

 

(2x0+1) (2x1+1) (2x2+1)

 

I also need to know how to add up sum’s

 

“Calculate the sum of terms 1 to 20”

 

This is done using Sn:

 

N(1st term + n term) /2

 

Note: N= term you going to find:

 

N=20

 

To find the 20th term:

 

Using the nth term = 20x2 + 1 = 41

 

Then 20(3 + 41)/2 = 440.

 

The sum of terms 1 to 20 is 440.

 

Another example:

 

Find the sum of 1 to 5000:

 

N(1st term + n term) / 2 :

 

5000(1+5000) / 2 = 12,502,500.

 

It’s much easier than adding all the numbers up from 1 to 5000, 1 + 2 + 3, you would be there all day.