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Im not 100% sure, but i'm thinking its this?

|dw:1330750567546:dw|

looks correct to me

That's correct.

good work

with the squared, since im really good at not noticing that

I'm trying to do a whole chapter in one night, so let's pull an all nighter?!:D

Uhh, im stuck D:

a[1]=0.375, a[k+1]=a[k]+0.25

Here's an example answer, if this helps. http://screensnapr.com/v/2PVSpz.png

I THINK it's a[2]=0.375+0.25=.625
a[3]=.625+0.25=0.875

oh, i added wrong, 0.875 -not using calculator-

a[4]0.875+.25=1.125
a[5]1.125+.25=1.375

When you do a_k, do you mean sub k? Because when I put sub I put [k]

yeah, when you use equation thing, sub-k is a_k, so that's why I use the _'s

So when I'm doing the nth term of the sequence and writing the function for it, what would that be?

a[n].375n+.25?

A(n) = a_1 + (n-1)d; d = common difference, a_1 = first term
would be the general form I'd use

Thank you! I think mine would work but yours seems more sophisticated.

Oh hey, your formula is the exact formula I'm using for my next questions.

a[1]=0, d=-2/3

well, if you test n=1, .375 + .25 = .625, which was the second term

0+(n-1)(-2/3)

hmm, another question..

I think the formula S[n]=n/2(a[1]+a[n]) would be used?

Just kidding far from that.

Don't even have a a[n]! Haha, what was I thinking :P

my source with the formulas for this says the (a[1] + a[n] is in numerator

http://screensnapr.com/v/x2890d.png But in that, where the hell did 9 come from?

n-1?

n-1, n = 10 => 10-1 = 9

So i got a[10]=1.5+19(.5)=11

a[20] sorry

yep, that's what I got as well

Then i got s[20]=10(1.5+11)

which equals 125

Yep, got 125 as well. :)

BOO! REAL WORLD APPLICATION PROBLEMS!

http://screensnapr.com/v/YRvm1X.png

15*16*17*18*19*20*21? Haha

Adding not multiplying, that would be an incredible amount of logs.

Uhh, a[1]=15, a[6]=21 and s[6]=21/2(15+21)=126

but it does appear that 126 is correct.