Using the summation formula, we find:
The two equations may be written:
Now, solve this system to determine and .
The sum of the first 5 terms of an arithmetic series is 85, and the sum of the first 6 terms is 123. Write the first 3 terms of the series.
Okay i tried, but ended up with strange numbers.
formulas:
tn=t1+(n-1)d
sn=n/2(2(t1)+(n-1)d)
please help
answer is d=7 t1=3
I actually wrote it out exactly like you did, but then i got help from another site as well and the person said that i could bring the fraction (5/2 & 6/2) over and use it to divide with 85 and 123. whew. I made it seem so difficult lol.
I blame my teacher for not showing the proper steps!!!
Oh and the two equations with 17 and 41 confuses me, so i didn't know what to do with them.