Question

Calculate the 100th partial sum of the sequence. 1, 3, 7, 10, ...
Do i just add all one hundred of these numbers!? 1+3+7+10+13 etc!?!?

Answer 1

that would be pretty tedious!

Answer 2

though I cant see a pattern in this series
you sure you have the question right?

Answer 3

yea lol im wondering that too

Answer 4

What is the pattern of the numbes?

Answer 5

can you post a quick screenshot of the material?

Answer 6

I think he just made it up for an example

Answer 7

are you sure the second term is not 4?

Answer 8

I see. Yes, you would have to manually solve it, or display it in summation

Answer 9

that would make it an arithmetic sequence

Answer 10

NO WAIT CRAM CRABBIT DAG GUMMIT I MADE A MISTAKE

Answer 11

The Sequence is 1, 4, 7, 10, i'm so sorry

Answer 12

???? lol

Answer 13

I'm gonna go nuts i need to CEASE with these flipping sequences

Answer 14

hmm can you post a quiick screenshot of the material? thus we could see what might be

Answer 15

thats an arithmetic sequence with commin difference of 3

Answer 16

yeap x-x

Answer 17

well
1 + 3 = 4 though
2nd term is 3 there

Answer 18

do you know the formula for the sum of n terms?

Answer 19

ohhh.. hmmm

Answer 20

@jdoe0001 - he later corrected it to 1,4,7,10

Answer 21

I'm trying to crack at it, but I can't think of a single formula. I could pop those numbers into a calculator and get an f(x) formula easy, but not for a blippin recursive sequence, god i hate these things

Answer 22

Sn = (n/2) [2a1 + (n - 1)d]

where a1 = first term and d = common difference

Answer 23

here a1 = 1, n = 100 and d = 3

Answer 24

\(\large {
\textit{what's }a_{\color{brown}{ 100}}?\qquad well
\\ \quad \\
a_{\color{brown}{ n}}=a_1+({\color{brown}{ n}}-1)d\qquad d\to \textit{common difference}\to 3
\\ \quad \\
a_{\color{brown}{ 100}}=a_1+({\color{brown}{ 100}}-1)\cdot 3
\\ \quad \\

\\ \quad \\
S_{\color{brown}{ n}}=\cfrac{{\color{brown}{ n}}}{2}(a_1+a_{\color{brown}{ n}})\impliedby \textit{sum of an arithmetic sequence}
\\ \quad \\
{\color{brown}{ n}}=100\qquad S_{\color{brown}{ 100}}=\cfrac{{\color{brown}{ 100}}}{2}(a_1+a_{\color{brown}{ 100}})
}\)

Answer 25

So 397!?

Answer 26

wait what has jdoe got here

Answer 27

nop try again

Answer 28

eheheh

Answer 29

oh cram it i multiplied something instead of divided gAK

Answer 30

You could also go solve the summation for it\[\Huge{\sum\limits_{i=0}^{99} (3i+1)} \]

Answer 31

S100 = 50[2 + (100-1)3]

Answer 32

oh how i prefer sigma equations....

Answer 33

Alright i'm clearly getting something wrong because i'm still getting 397

Answer 34

oh WAIT

Answer 35

wait no yeah i'm going something wrong

Answer 36

work out inner bracket first 99*3
then add 2
then multiply by 50

Answer 37

it was the parentheses, dag gummit, so do you have 14950?

Answer 38

yea

Answer 39

fantastic

Answer 40

remember PEDMAS