
Arithmetic Sequences
Hi, I have 2 problems I do not understand; could anyone explain what exactly is meant by u1 and d? and how to solve for the said variables?
Thanks!
1A sequence is defined by
Un=(717n)/2
Find U1 and d.
Another problem, if you can explain one, I'm sure I can understand the other one.
2 A sequence is defined by Un=3n2
Find u1 and d.
Oh, and when I wrote Un and U1, I meant U with a subscript of n, and U with a subscript of 1. Sorry, I don't know how to make the subscripts appear.
Thanks in advance!

(1.) u1 = (71  7(1))/2 = 32
u2 = (71  7(2))/2 = 28.5
u3 = (71  7(3))/2 = 25
d = 25  28.5 = 3.5
d = 28.5  32 = 3.5
(2.) Use the same procedure as in #1.