1. Find the sum of the first 21 terms of the arithmetic sequence given by the formula an = n+5
I see that I have to plug in numbers and get the terms...but i'm sure there's a shorter way to do this instead of plugging in 21 numbers.
2. The following infinite geometric series will have a finite sum: 1001/6 + 1001/36 + 1001/216 + 1001/1296
Not sure...
6 answers
http://www.regentsprep.org/Regents/math/algtrig/ATP2/ArithSeq.htm
you should know the nth sum of an A.S. is
Sn = n/2 (2a + (n-1)d)
Your sequence has
a=6
d=1
For the G.S. you must have |r| < 1.
What are a,r for this sequence?
Sn = n/2 (2a + (n-1)d)
Your sequence has
a=6
d=1
For the G.S. you must have |r| < 1.
What are a,r for this sequence?
Is the answer 336?
That's what I get.
Yes,thanks
Pls can u help me to solve: x+y+z=1,x^2+y^2+z^2=34 and x^3+y^3+z^3=94
1 answer