Question

14. What is the sum of the arithmetic series 18 (on top) series symbol t=1 on bottom then (5t-4) a. 783
b1566
c819
d86

Answer 1

@Opcode

Answer 2

Summation right? So you mean this:
\[\sum_{t=1}^{18}(5t-4)\]

Answer 3

YES!!!

Answer 4

Have you learned basic summation? What do you not understand?

Answer 5

I have I just drew a complete blank.

Answer 6

Hmm, okay do you want to attempt the problem on your own, and then want me to check your answer? I'm sure you can do it the problem isn't too hard, if you don't know where to start just ask me. :-)

Answer 7

d?

Answer 8

first term a=5*1-4=1
last term l=5*18-4=90-4=86
n=18
\[sn=\frac{ n }{ 2 }\left( a+l \right)\]
calculate s18

Answer 9

No, it is not C or D.
Summation works like:
\[\sum_{t \mathop =m}^n a_t = a_m + a_{m+1} + a_{m+2} +\cdots+ a_{n-1} + a_n\]

Answer 10

T represents the index of the summation.
M represents the lower limit of the summation.
N represents the upper limit of the summation.

\[\sum_{t=1}^{18}(5t-4)\]

Think of it like 18 is the number we want to go to, and that t = 1 and 1 being the start.

Here is a simple example to get you started:
\[\sum_{n=2}^{5}(n) = 2 + 3 + 4 + 5 = 14\]

Do you see how that works?

Answer 11

Yes I understand that

Answer 12

Oh I understand thank you

Answer 13

Okay here is one that is a little bit more complex:
\[\sum_{x = 1}^{5}(x^2 + 2)\]

Now do you see how to do that?
Here is a hint:
\[\sum_{x = 1}^{5}(x^2 + 2) = (1^2 + 2) + (2^2 + 2) + (3^2 + 2) + (4^2 + 2) + (5^2 + 2)\]

See how x = 1 is the number we start at and the 5 on top of the capital sigma the number we go to?

Answer 14

yes I do

Answer 15

I got it right(: Thank you so much

Answer 16

Okay, well I might as well right out the answer just for others who may read this:
\[\sum_{t=1}^{18}(5t-4) = (5 \times 1 - 4) + (5 \times 2 - 4) + (5 \times 3 - 4) \dots = 783\]

If you don't understand just say. :-)

Answer 17

Thank you bunches

Answer 18

No problem, glad you understand. :D