Question

Sequence help

Answer 1

n>1

A(100) = 1+2+3+...+100 =5,050

What is A(200) ?

Answer 2

Help

Answer 3

I'm guessing

A(200) = 1+2+3+...+200

It's an arithmetic sequence. You can do it the way Guass originally did it (supposedly), or use the formula for a sum of a sequence.

Answer 4

I have the answer of 20,100. Let me try it that way real quick!

Answer 5

that seems reasonable

Gauss's method means adding the first and last, then the second first and second last, and so on

eg.
1+200 = 201
2+199 = 201
3+198 = 201

See the pattern?

There should be exactly 100 of those 201's

Answer 6

ok. Why can;t you use this arithmetic seq formula:

An=a1+(n-1)*d
where d is the difference, a1 is 1st term, and n is the number u want

Answer 7

You can.

Answer 8

But Gauss probably did not know that.

Answer 9

I am so stupid. Can you show me how I can plug those #'s in the formula I typed to get that ans. I can't get it

Answer 10

Keep in mind that isn't the SUM formula, that's the formula for a term.

Answer 11

can u show me

Answer 12

http://www.regentsprep.org/regents/math/algtrig/atp2/ArithG3.gif

first term a1
number of terms n
last term an

Answer 13

1+2+3+...+200
First term is 1
number of terms is 200 (since you're counting to 200)
last term is of course 200