Question

Arithmetic Sequence :
If Sn = -441 for the series 19 + 15 + 11 + ... + tn, find n.

Answer 1

\[\huge \textbf{Welcome To Openstudy}\]

Answer 2

What is the last term you are given??

Answer 3

i think it is n or \(\huge{t_n}\)

Answer 4

You are asking to whom??

Answer 5

Remember :
\[\Huge{S_n=\frac{n}{2}{2n+(n-1)d}}\]

Answer 6

I think the Sum is given and we have to find the n..

Answer 7

Formula for sum is:

\[\huge \color{green}{ S_n = \frac{n}{2}(2a + (n-1)d)}\]

Answer 8

Oh yes sorry

Answer 9

i put n there

Answer 10

Here,

You have \(S_n = -441\)
\(a = 19\)
\(d = 15 -19 = -4\)
Just plug in these values in the formula and then solve for n...