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# Really fast (and easy) maths help! PLEASE!?

Okay, I have a test tomorrow which is worth only like 5% of my overall maths grade, but I really don't want to fail (it's 2 credits, and I need 80 at the end of the year).

Just fast:

In my textbook (for an example) it says: a: 23, d: 6, n: ?

Tn= a + (n-1) d

Tn= 23 + (n-1) 6

Tn= 6n + 17

I don't understand how it jumps from 23 + (n-1)d to 6n + 17.

PLEASE PLEASE EXPLAIN! Oh no :(

### 2 Answers

- Ravi DhillonLv 59 years agoFavorite Answer
here a(23) is the first term of AP

d(6) is the common difference

Tn is the nth term of the AP

the AP thus =23,29,35,41,47.....

here 5th term is 47, ie n=5. To find the 5th term , write the formula

Tn=a+(n-1)d and put the values of a,d and n.

T5=23+(5-1)*6

T5=23+4*6

T5=23+24

T5=47

that is ie 5th term of AP=47

similarly if you want to find the 100th term of AP ie n=100, then

T100=23+(100-1)6

T100=23+99*6

T100=23+594

T100=617. Hope it helps .Good luck .