Question

how do I find the n th term in the following sequence?

1,3,6,10,15,21... a30

Answer 1

we seem to be doing the same hw :D

Answer 2

an=a1+(n−1)d

Answer 3

isn't that when it is constant?

Answer 4

yeah, i didn't see that....thinking ;/

Answer 5

did you try the geometric sequence formula?

Answer 6

\[a _{n}=a _{1}r ^{n-1}\] ?

Answer 7

this is
1
1+2
1+2+3
1+2+3+4
1+2+3+4+5

Answer 8

formula is
\[\frac{n(n+1)}{2}\]

Answer 9

yes

Answer 10

and so
\[a_{30}=\frac{(30)(31)}{2}=15\times 31=465\]

Answer 11

thank you!!!!!

Answer 12

yw