I can't remember the formula for this question.
The first term of an arithmetic sequence is -5, and the tenth term is 13. Find the common difference.

Question

I can't remember the formula for this question. 
The first term of an arithmetic sequence is -5, and the tenth term is 13. Find the common difference.

myininaya · Answer

@Kit_Kat_Nat_<3 I'm testing something. 
Is this question in the feedback section or the math section? 
Just used the slope formula by the way.

camerondoherty · Answer

Feedback...

nnesha · Answer

this is in feedback section

anonymous · Answer

Oh. Whoops. I thought I was posting this in the math section, sorry, @myininaya

myininaya · Answer

Oh its okay. I'm not sure anymore either where things are.

anonymous · Answer

Lol. I clicked on a question in here and forgot to switch back to math.

myininaya · Answer

$$d=\frac{a_{10}-a_1}{10-1}$$ <this is what I meant by slope formula

anonymous · Answer

I haven't ever used that formula before, do you know what the formula is for an arithmetic sequence is? :)

compassionate · Answer

I don't know what to believe anymore @myininaya

myininaya · Answer

$$a_{10}=a_1+(10-1)d  \  a_{10}-a_{1}=(10-1)d \ \frac{a_{10}-a_{1}}{10-1}=d$$
Should be familiar with this equation ...

nnesha · Answer

yes for       |dw:1416527770914:dw|