Identify the 25th term of the arithmetic sequence 2, 1 3/5, 1 1/5 …

−73/5

−8

−122/5

−13

Question

Identify the 25th term of the arithmetic sequence 2, 1 3/5, 1 1/5 …

−73/5	

−8

−122/5

−13

hartnn · Answer

do you know what is an arithmetic sequence ?
can you find common difference ?

anonymous · Answer

yea the common difference can be founded by adding the biggest from the smallest right?

hartnn · Answer

not actually,

common difference 'd' is the difference between the consecutive terms 

like d = 2nd term - 1st term = 3rd term - 2nd term  = and so on ...

anonymous · Answer

oh okay okay so id take 2 - 1 3/5
wich equals 2/5

hartnn · Answer

actually 
2nd term is 1 3/5 and 1st term is 2

so d = 1 3/5 - 2 = -2/5
got this ?

anonymous · Answer

oh okay yea got it

hartnn · Answer

and 1st term = a1 = 2

now plug those in the general formula 
$\large a_n = a_1 + (n-1)d$

anonymous · Answer

-7 2/3

anonymous · Answer

so its A.

anonymous · Answer

THANKS

hartnn · Answer

2-48/5  = 10 -48/5 = -38/5  = - 7 3/5 
yes, thats correct :)
welcome ^_^

whpalmer4 · Answer

It's important to solidify your understanding of the correct meaning of "common difference" (and similarly "common ratio" for geometric sequences) as getting it backwards will lead to many wrong answers...The common difference is the value added to the first term to get the second term, as you can see from the formula $$a_n = a_1 + (n-1)d$$where we find subsequent terms by repeatedly adding the common difference $d$ to the first term.