Question

the 10th term of an arithematic series is 34, and the sum of the first 20 terms is 710. determine the 25th term

Answer 1

\[a _{n}=a _{1}+(n-1)d\]

Answer 2

\[34=a _{1}+(10-1)d\]

Answer 3

dont u use the formula sn = n/2 (2a (n-1)d)
For the sum of the arethematic SERIES, NOT SEQUESNCE

Answer 4

@nupursehrawat get here.. and see how it goes ;) ... (we can chat there too. ) http://www.twiddla.com/807035

Answer 5

tell me when you're there ...

Answer 6

@nupursehrawat ... are you there?

Answer 7

@nupursehrawat check this out ...

Answer 8

She told you that you couldn't use that formula.

Answer 9

That's what stumped me. I thought we needed that formula.

Answer 10

now we have...

\[\Large a_1=34-9\cdot 3\]
\[\Large a_1=7\]

Now substitute \[\LARGE a_1=7 \quad \quad d=3\]

in this equation...

\[\LARGE a_{25}=a_1+(n-1)d\]

Answer 11

look again , she was confused, and asked you if we should use formula of Sn instead of a_n but she forgot this : \[\huge ?\]

Answer 12

I guess you and I are the only ones still interested in the problem.

Answer 13

100% agree !

Answer 14

no im
here

Answer 15

My mom Called me SOOOOOOOOORY

Answer 16

Ok then check out link I posted before, Hope that helps , if it doesn't I don't know other way !

Answer 17

It Does Help Thank You Verryyyy MUCH Appreciate It :)

Answer 18

My preasure ... @Mertsj could do this one easily I'm extremely sure, but he thought that you're not allowed to use the formula I used LOL ...

Answer 19

But Its Hard To Understand

Answer 20

What You Did In The Picture

Answer 21

do you know two main formulas of arithmetic sequences ?

Answer 22

yes

Answer 23

do you mind if I ask you to write them for me ?

Answer 24

Sn = N/2 (2a (n-1)D
Sn = (a + Tn)

Tn = term number
a = first number

Answer 25

other formula ?

Answer 26

Its ok I Will ask my teacjer for help
Bye

Answer 27

...as you wish !