<PRE><B>Question 48756</B>
&lt;pre&gt;&lt;font size = 5&gt;&lt;b&gt;
Use the arithmetic sequence of numbers

2, 4, 6, 8, 10,

what is the sum of the first 30 terms?
I came up with 930, am I correct? 

2nd term - 1st term =  4 - 2 = 2
3rd term - 2nd term =  6 - 4 = 2
4th term - 3rd term =  8 - 6 = 2
5th term - 4th term = 10 - 8 = 2

These are all 2, so the common difference, d = 2.

The sum of the first n terms is given by the formula

S&lt;sub&gt;n&lt;/sub&gt; = n[2a&lt;sub&gt;1&lt;/sub&gt; + (n-1)d]/2

n = 30, a&lt;sub&gt;1&lt;/sub&gt; = 2, d = 2

S&lt;sub&gt;30&lt;/sub&gt; = 30[2(2) + (30-1)(2)]/2

S&lt;sub&gt;30&lt;/sub&gt; = 30[4 + (29)(2)]/2

S&lt;sub&gt;30&lt;/sub&gt; = 30(4 + 58)/2

S&lt;sub&gt;30&lt;/sub&gt; = 30(62)/2 

S&lt;sub&gt;30&lt;/sub&gt; = 1860/2

S&lt;sub&gt;30&lt;/sub&gt; = 930

Looks like you&#39;re right!

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Also how do I type in the term or subscript? 
Ex: a&lt;sub&gt;1&lt;/sub&gt; a&lt;sub&gt;2&lt;/sub&gt; a&lt;sub&gt;3&lt;/sub&gt;.....

With HTML tags.  To type

a&lt;sub&gt;1&lt;/sub&gt; 

you have to type 

a&lt; sub&gt;1&lt; /sub&gt;

except you close those spaces after the &lt; &#39;s. I didn&#39;t 
here because if I had you&#39;d have only seen a&lt;sub&gt;1&lt;/sub&gt;.
I don&#39;t type the tags individually.  That takes too long.
I put the tags in after I finish, using &#39;cut and paste&#39;.

Edwin&lt;/pre&gt; </PRE>