Noobpatty
ʎʇʇɐdqoou
+194|6599|West NY
if
0 = 720,500(1.022)x - 1,548,800
how do I find X?
help is greatly appreciated
-N
presidentsheep
Back to the Fuhrer
+208|6206|Places 'n such

Noobpatty wrote:

if
0 = 720,500(1.022)x - 1,548,800
how do I find X?
help is greatly appreciated
-N
If its to the power x, take logs is always the key.

x = (ln(1,548,800/720,500))/ln(1.022)

edit: lol  sad face
double edit: forgot a ln and messed up a digit.

Last edited by presidentsheep (2010-01-26 16:37:55)

I'd type my pc specs out all fancy again but teh mods would remove it. Again.
Peter
Super Awesome Member
+494|6647|dm_maidenhead

Noobpatty wrote:

if
0 = 720,500(1.022)x - 1,548,800
how do I find X?
help is greatly appreciated
-N
0 = 720,500(1.022)x - 1,548,800
add 1,548,800 to both sides
1,548,800 = 720,500(1.022)x
divide both sides by 720,500
2.1496 = 1.022x
take logs
log1.0222.1496 = x
x = 35.17
Noobpatty
ʎʇʇɐdqoou
+194|6599|West NY

presidentsheep wrote:

Noobpatty wrote:

if
0 = 720,500(1.022)x - 1,548,800
how do I find X?
help is greatly appreciated
-N
If its to the power x, take logs is always the key.

x = (ln(1,548,800/720,500))/ln(1.022)

edit: lol  sad face
double edit: forgot a ln and messed up a digit.
Well I kinda made a wrong move,
1548800= 720500(1.022)x
so then
2.14961..=1.022^x
and then
log1.0222.14 = x
right?
presidentsheep
Back to the Fuhrer
+208|6206|Places 'n such

Noobpatty wrote:

presidentsheep wrote:

Noobpatty wrote:

if
0 = 720,500(1.022)x - 1,548,800
how do I find X?
help is greatly appreciated
-N
If its to the power x, take logs is always the key.

x = (ln(1,548,800/720,500))/ln(1.022)

edit: lol  sad face
double edit: forgot a ln and messed up a digit.
Well I kinda made a wrong move,
1548800= 720500(1.022)x
so then
2.14961..=1.022^x
and then
log1.0222.14 = x
right?
right.
I'd type my pc specs out all fancy again but teh mods would remove it. Again.
Bevo
Nah
+718|6766|Austin, Texas
eek

got about 20 minutes, anyone fluent in calc?

ive got 2 problems involving l'hospital's rule.


47. lim (x -> 1) ((x/(x-1)) - (1/ln(x)))

I somehow reduced this one to (1/x)/ln(x) + 1 - (1/x), but this leaves me with 1/0, which I don't want. I need 0/0. If I were to derive once more, I'd get the correct answer of 1/2.

64. lim (x -> inf) ((2x-3)/(2x+5))^(2x+1)

Got this to (2x+1)*(ln(2x-3) - ln(2x+5)) which is also no bueno. need lny = -8 so that y = e^-8.

Wolfram is no help on either of them. Thoughts?
liquidat0r
wtf.
+2,223|6872|UK
@Bevo

If you're reading this then you're probably in class already ... sorry, I got bored and started watching House M.D instead
Bevo
Nah
+718|6766|Austin, Texas
Np. I figured out the first one and got close on the second. For the first one I accidently derived the top and distributed the bottom without deriving both. The second... Well I'm at a loss.
Bevo
Nah
+718|6766|Austin, Texas

Bevo wrote:

Np. I figured out the first one and got close on the second. For the first one I accidently derived the top and distributed the bottom without deriving both. The second... Well I'm at a loss.
lol, fucking hell

He asked at the beginning of class if we had any questions over the HW. I said 64. He did the first half of the problem exactly like I did, and he was like "you should be able to finish it"

I just worked out what I could and put down an incorrect answer. He's a terrible TA.
Ryan
Member
+1,230|7088|Alberta, Canada

Bevo wrote:

eek

got about 20 minutes, anyone fluent in calc?

ive got 2 problems involving l'hospital's rule.


47. lim (x -> 1) ((x/(x-1)) - (1/ln(x)))

I somehow reduced this one to (1/x)/ln(x) + 1 - (1/x), but this leaves me with 1/0, which I don't want. I need 0/0. If I were to derive once more, I'd get the correct answer of 1/2.

64. lim (x -> inf) ((2x-3)/(2x+5))^(2x+1)

Got this to (2x+1)*(ln(2x-3) - ln(2x+5)) which is also no bueno. need lny = -8 so that y = e^-8.

Wolfram is no help on either of them. Thoughts?
Fuck, I hate calculus. Limits were the first thing we learned, and I still don't understand what the frig I'm doing.
Bevo
Nah
+718|6766|Austin, Texas

Ryan wrote:

Bevo wrote:

eek

got about 20 minutes, anyone fluent in calc?

ive got 2 problems involving l'hospital's rule.


47. lim (x -> 1) ((x/(x-1)) - (1/ln(x)))

I somehow reduced this one to (1/x)/ln(x) + 1 - (1/x), but this leaves me with 1/0, which I don't want. I need 0/0. If I were to derive once more, I'd get the correct answer of 1/2.

64. lim (x -> inf) ((2x-3)/(2x+5))^(2x+1)

Got this to (2x+1)*(ln(2x-3) - ln(2x+5)) which is also no bueno. need lny = -8 so that y = e^-8.

Wolfram is no help on either of them. Thoughts?
Fuck, I hate calculus. Limits were the first thing we learned, and I still don't understand what the frig I'm doing.
Well erm this is Calc 2, so don't expect to know how to do these.

Limits are annoying as fuck, indeed. We did 3 limit problems today in about 45 minutes. The last 25 minutes the TA spent writing and explaining the last problem... half of the class was laughing towards the end because we had no fucking idea what he was doing. I got lost somewhere after 15 minutes and just tuned him out completely.
liquidat0r
wtf.
+2,223|6872|UK
@Bevo Do you know what the answer to the second one is meant to be?
Bevo
Nah
+718|6766|Austin, Texas

liquidat0r wrote:

@Bevo Do you know what the answer to the second one is meant to be?
e^-8, wolfram says

I got inf/8 once, and then when I re-did it I got 1/1.
liquidat0r
wtf.
+2,223|6872|UK
Yeah I keep getting 1/1
Ryan
Member
+1,230|7088|Alberta, Canada

Bevo wrote:

Ryan wrote:

Bevo wrote:

eek

got about 20 minutes, anyone fluent in calc?

ive got 2 problems involving l'hospital's rule.


47. lim (x -> 1) ((x/(x-1)) - (1/ln(x)))

I somehow reduced this one to (1/x)/ln(x) + 1 - (1/x), but this leaves me with 1/0, which I don't want. I need 0/0. If I were to derive once more, I'd get the correct answer of 1/2.

64. lim (x -> inf) ((2x-3)/(2x+5))^(2x+1)

Got this to (2x+1)*(ln(2x-3) - ln(2x+5)) which is also no bueno. need lny = -8 so that y = e^-8.

Wolfram is no help on either of them. Thoughts?
Fuck, I hate calculus. Limits were the first thing we learned, and I still don't understand what the frig I'm doing.
Well erm this is Calc 2, so don't expect to know how to do these.

Limits are annoying as fuck, indeed. We did 3 limit problems today in about 45 minutes. The last 25 minutes the TA spent writing and explaining the last problem... half of the class was laughing towards the end because we had no fucking idea what he was doing. I got lost somewhere after 15 minutes and just tuned him out completely.
Well I'm in Calculus AP, and we are starting this shit in the next semester (which starts Monday).
I got 32 out of 50 on the midterm, but our teacher lowered the total from 60 to 50, otherwise everyone would have pretty much failed. She's a fucking shit teacher.
Bevo
Nah
+718|6766|Austin, Texas

Ryan wrote:

Well I'm in Calculus AP, and we are starting this shit in the next semester (which starts Monday).
I got 32 out of 50 on the midterm, but our teacher lowered the total from 60 to 50, otherwise everyone would have pretty much failed. She's a fucking shit teacher.
Calc AP =/= Calc 1 in college

You may get the credit, but my friends who took Calc AP and passed the test fine went and took calc 1 in college because they said calc 2 was far too hard. It's not really the same thing.

Don't worry, it's difficult. I breezed through every area of math before calc and I barely squeaked by with a B last semester in calc 1.
lxcpikiman
imbad @ bf2
+70|6841|Toronto-Canada
can someone help me with binary, specifically conversion when the number is decimal.
something like something this.

1234.789
i got this so far
10011010010.???
presidentsheep
Back to the Fuhrer
+208|6206|Places 'n such

lxcpikiman wrote:

can someone help me with binary, specifically conversion when the number is decimal.
something like something this.

1234.789
i got this so far
10011010010.???
fuck i hated binary...
I'll look in my old textbook to see if i can remember anything bout decimals.
I'd type my pc specs out all fancy again but teh mods would remove it. Again.
Flaming_Maniac
prince of insufficient light
+2,490|6952|67.222.138.85
102 101 100 . 10-1 10-2 etc.

.25 = 2(10-1) + 5(10-2)

23 22 21 20 . 2-1 2-2 etc.

.75 in binary is .11 because it =

1(2-1) +1(2-2)  = 1(1/2) + 1(1/4)
Winston_Churchill
Bazinga!
+521|6984|Toronto | Canada

lxcpikiman wrote:

can someone help me with binary, specifically conversion when the number is decimal.
something like something this.

1234.789
i got this so far
10011010010.???
Google ftw

http://acc6.its.brooklyn.cuny.edu/~gurw … 2tool.html

1234.789 = 10011010010.110010011111101111100111011
mkxiii
online bf2s mek evasion
+509|6481|Uk

Flaming_Maniac wrote:

23 22 21 20 . 2-1 2-2 etc.
so 1234.789=10011010010.1100101??


well i think that =1234.7890125 but i guess youre rounding

edit:please recheck as that was in my head
edit2:ignore this, the unrounded answer is about 2 inches above it

Last edited by mkxiii (2010-02-09 11:58:44)

Flaming_Maniac
prince of insufficient light
+2,490|6952|67.222.138.85
yeah you got the idea, faggot teacher that gave you a stupid pattern instead of something that actually terminates after a reasonable amount of numbers after the binary point...
mkxiii
online bf2s mek evasion
+509|6481|Uk

Flaming_Maniac wrote:

yeah you got the idea, faggot teacher that gave you a stupid pattern instead of something that actually terminates after a reasonable amount of numbers after the binary point...
thats what i was thinking, i figured if it was just to test whether you could do decimals it would surely terminate after 5 or 6
lxcpikiman
imbad @ bf2
+70|6841|Toronto-Canada
yeah i could have used a binary converter but i wanted to learn how to do it.
andi think i got it now.
Bevo
Nah
+718|6766|Austin, Texas
Calling all liquidators.

Doing a series sum (n = 1 -> inf) e^n / 3^(n-1)

Ive figured out that the terms approach zero (e/3 < 1 and raised to the power of some n), but it has to approach 0 and be decreasing both to be convergent. The problem is, I have no idea what the difference is. The terms decrease... towards zero, just like the sum of 1/n would. But that's divergent.

what the hell is the difference?

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