Question

The sum of the first "n" terms of a series is Sn = n^2 + 4n. Find t1, t2, t3

Answer 1

ok

Answer 2

u wrote\[s _{n}=n ^{2}+4n\]

Answer 3

sorry

Answer 4

need time

Answer 5

kk np

Answer 6

t1 = a1 = S1
put n=1 to Sn

Answer 7

i think the series will b 5+7+9+.....................+(2n+3)

Answer 8

so t1=5
t2=7
t3=9

Answer 9

Can I get explanations on how to do it? o.O Not just the answers?

Answer 10

if u put n=1 u will get 2n+3=2*1+3=5

Answer 11

so t1=5

Answer 12

Why do you put n=1? How do you know to make it 1 and not any other number? o.O

Answer 13

when n=1 we will get the first term of the series

Answer 14

when we will put n=2 in (2n+3) then we will get the second term of the series

Answer 15

wait if u put in the second term doesnt that equal the first term plus the second term?

Answer 16

no

Answer 17

when u will put n=2 in the equation \[s _{n}=n ^{2}+4n\]

Answer 18

because the equation Sn = n^2 + 4n is for the sum and n is the terms in the series. So if you put 1 in you'll get the first term because it doesnt get added to anything, but if you put 2 terms in the equation you will get t1 + t2

Answer 19

then u will get the sum of 1st term and second term

Answer 20

Yea okay lol thats wat i meant

Answer 21

so youd have to subtract the previous terms to get the one ur looking for. Correct?

Answer 22

ya

Answer 23

Kay! Thank you! :)

Answer 24

thanks for medal

Answer 25

welcome

Answer 26

Np you deserved it ^_^

Answer 27

anyway may i know the name of ur country and class

Answer 28

United States and I'm taking Pre-calculus right now

Answer 29

which class u r reading

Answer 30

?

Answer 31

i mean r u a student of Advance level or something else

Answer 32

Um... I don't know what you call it from where you're from, but I'm taking Honors Pre-Calc which is like the more advanced course of Pre Calc here ^_^

Answer 33

understood

Answer 34

i m frm bangladesh

Answer 35

I see! Nice to meet you ^_^

Answer 36

nicve to meet u

Answer 37

nice to meet u