radnorgardens
New member
- Joined
- Dec 2, 2014
- Messages
- 26
Question: The first term of an arithmetic series is 16 (a). The 30th term (n) is 100. Calculate S30.
So again, I have the formula:
Sn=n/2[2(a)+(n-1)d].
Using the data above:
S30=30/2[2(16)+(30-1)d]
S30=30/2[32+29d]
Again, I don't understand my next step, or maybe my initial steps are completely wrong. I don't know what to do with the '100', nor 'd' (the common difference). Another attempt:
1st term = 16
30th term = 100
Stuck!
Thanks for any pointers.
So again, I have the formula:
Sn=n/2[2(a)+(n-1)d].
Using the data above:
S30=30/2[2(16)+(30-1)d]
S30=30/2[32+29d]
Again, I don't understand my next step, or maybe my initial steps are completely wrong. I don't know what to do with the '100', nor 'd' (the common difference). Another attempt:
1st term = 16
30th term = 100
Stuck!
Thanks for any pointers.