TI-89 Help

dlinkwit27 · 6th October 2004, 14:13

I was observing a pre-calc class today and they were using their calcs to different equations, but when they tried d(.25x^4,x,.001) they got a domain error. I couldn't figure out why. Anyone have any ideas?

shakey_snake · 6th October 2004, 19:27

try putting quotes around the x so it would read:

d(.25x^4,"x",0.001)

Thats what I do on my 83+SE using the symbolic app.

k_rock923 · 6th October 2004, 19:44

got the same thing on mine. not sure why.

dlinkwit27 · 6th October 2004, 22:13

weird thing is that when I do the same equation, but replace .001 with a larger number like 5, it works fine. I maybe it becomes out of the minimum bounds....somehow...

Bilbo Baggins · 6th October 2004, 22:36

Some numbers just werent meant to be added up.

dlinkwit27 · 6th October 2004, 23:03

seems to be that way.

k_rock923 · 6th October 2004, 23:11

they were doing that in pre calc? I didn't do that until the last month or so of pre-calc and didn't really know what I was doing at the time. We just strated using that notaion in AP calculus and it confused the hell outof me.

dlinkwit27 · 6th October 2004, 23:12

i think it's pre calc. maybe calc I. idk. either way, they can't do that particular equation, and it pissed me off that it wouldn't work.

shakey_snake · 6th October 2004, 23:32

what is the definition of the arguments? It could be that the final argument (ie 0.001) is how many times you want to take the derivitive (what the "d()" function is) so it would have to be a counting number (defn: positive nonzero integer).

sidenoteIt was definitely) not a precalc class.

Mrs_Mia_Wallace · 6th October 2004, 23:40

I am in college and I never used calculators like that. We still do our math with pen and paper...or with a Computer if the previous fails.

Mia

dlinkwit27 · 7th October 2004, 01:17

arguments are as folows "expression, variable (which is in relation to), point at which to take the derivitive"

k_rock923 · 7th October 2004, 01:27

i tried doing it the old fashioned way and then stopped because i forgot how to raise a binomial to the fourth

Phyltre · 7th October 2004, 04:45

This is why I never, never take any math course harder than Statistics 101.

shakey_snake · 7th October 2004, 05:10

put the expression argument in quotes
or put the expression argument in Y-var and use that Y-Var in the d() expression.

Kinetik* · 7th October 2004, 22:13

I'll stick with College Algebra, where my TI-89 can do everything we're assigned to do in the class.

Edit: If you ignore the fact that I just dropped out of college, that is.

dlinkwit27 · 7th October 2004, 23:59

Quote:

Originally posted by shakey_snake
put the expression argument in quotes
or put the expression argument in Y-var and use that Y-Var in the d() expression.

didn't work, but oh well.

k_rock923 · 8th October 2004, 01:47

do you know what the actual answer is? .25x^4 let's see. power rule would make it 3(.25)x^3 so that gives .75x^3 and when you use .001, it gives you (.75)(.001^3)= 7.5 x 10^-10? um. . .

Psythik · 8th October 2004, 02:00

And I thought sophmore geometry was confusing...

Cognition · 8th October 2004, 06:19

It's not a number that's really huge or really tiny is it? Cause that'd give an error.

dlinkwit27 · 8th October 2004, 14:05

Quote:

Originally posted by Cognition
It's not a number that's really huge or really tiny is it? Cause that'd give an error.

that's what I was figuring, but the 89 can handle some pretty small numbers I thought.

OutlawJim · 8th October 2004, 15:02

i think my brain exploded from the complicatedness of the maths in this thread. thank god i never use it anyhow

squall14716 · 9th October 2004, 03:16

What exactly are you trying to do? Take the derivative of .25x^4 at 0.001?

The derivative of .25x^4 is x^3. Plug in 0.001.

The derivative of x^n is n(x)^(n-1).

k_rock923 · 9th October 2004, 03:26

I see an error in my own calculations. I was tired. oops.

shakey_snake · 9th October 2004, 17:19

Quote:

Originally posted by k_rock923
I see an error in my own calculations. I was tired. oops.

Yeah, I took Calc AB my senior Year in HS. So I figured I could Clep out of the 1 College Algebra class I needed for an intercultural Studies Major...
I got the Practice test and realized I've forgotten everything, in the matter of 15 months!
I'm looking at a practice test for math class that is equivilent to something I took Sophmore year of HS and I can't rember how to factor simple Trinomials.
So much can be forgotten soooo quickly.

squall14716 · 9th October 2004, 22:01

Post a trinomial then. I'm sure someone can factor it.

k_rock923 · 9th October 2004, 23:44

x^2+2x+2

dlinkwit27 · 9th October 2004, 23:57

you gotta use the quadratic equation:

[-b +/- sqrt(b^2 - 4ac)] / (2a)

I got (off the top of my head) (3+1i) * (-2-1i) as the factors.

k_rock923 · 10th October 2004, 00:11

yea, but i meant you can't factor it into two real binomials.

shakey_snake · 10th October 2004, 00:11

*whispers @squall* Don't worry, I realize the winking smiley indicates sarcasum, but lets not tell everyone else, Ok?

whiteflip · 10th October 2004, 04:16

the ti89 needs a backlight, so does my ti83. mia you are a trooper but you should try to use one of teaxa's instruments. they are quite good.

6th October 2004, 14:13	#1
dlinkwit27 has no CT (Forum King) Join Date: Sep 2000 Posts: 13,236	TI-89 Help I was observing a pre-calc class today and they were using their calcs to different equations, but when they tried d(.25x^4,x,.001) they got a domain error. I couldn't figure out why. Anyone have any ideas? ::Deviant Me::Last.fm::WhatPulse Stats::Folding @ Home

6th October 2004, 19:27	#2
shakey_snake Forum Domo Join Date: Jan 2004 Location: Everyone, get over here for the picture! Posts: 4,313	try putting quotes around the x so it would read: d(.25x^4,"x",0.001) Thats what I do on my 83+SE using the symbolic app. elevatorladyelevatorladyelevatorladyelevatorladyelevatorladylevitateme

6th October 2004, 19:44	#3
k_rock923 \m/ (Forum King) Join Date: Jul 2003 Location: /bin/bash Posts: 7,850	got the same thing on mine. not sure why. Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway.

6th October 2004, 22:13	#4
dlinkwit27 has no CT (Forum King) Join Date: Sep 2000 Posts: 13,236	weird thing is that when I do the same equation, but replace .001 with a larger number like 5, it works fine. I maybe it becomes out of the minimum bounds....somehow... ::Deviant Me::Last.fm::WhatPulse Stats::Folding @ Home

6th October 2004, 23:03	#6
dlinkwit27 has no CT (Forum King) Join Date: Sep 2000 Posts: 13,236	seems to be that way. ::Deviant Me::Last.fm::WhatPulse Stats::Folding @ Home

6th October 2004, 22:36	#5
Bilbo Baggins Wind Chime of the Apocalypse Join Date: May 2000 Location: The Forest Posts: 17,228	Some numbers just werent meant to be added up.

6th October 2004, 23:11	#7
k_rock923 \m/ (Forum King) Join Date: Jul 2003 Location: /bin/bash Posts: 7,850	they were doing that in pre calc? I didn't do that until the last month or so of pre-calc and didn't really know what I was doing at the time. We just strated using that notaion in AP calculus and it confused the hell outof me. Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway.

6th October 2004, 23:12	#8
dlinkwit27 has no CT (Forum King) Join Date: Sep 2000 Posts: 13,236	i think it's pre calc. maybe calc I. idk. either way, they can't do that particular equation, and it pissed me off that it wouldn't work. ::Deviant Me::Last.fm::WhatPulse Stats::Folding @ Home

6th October 2004, 23:32	#9
shakey_snake Forum Domo Join Date: Jan 2004 Location: Everyone, get over here for the picture! Posts: 4,313	what is the definition of the arguments? It could be that the final argument (ie 0.001) is how many times you want to take the derivitive (what the "d()" function is) so it would have to be a counting number (defn: positive nonzero integer). sidenoteIt was definitely) not a precalc class. elevatorladyelevatorladyelevatorladyelevatorladyelevatorladylevitateme

6th October 2004, 23:40	#10
Mrs_Mia_Wallace has a crush on Bilbo (Forum Queen) Join Date: Dec 2002 Location: Switzerland Posts: The starting points at a racetrack. Posts: 3,060	I am in college and I never used calculators like that. We still do our math with pen and paper...or with a Computer if the previous fails. Mia

7th October 2004, 01:17	#11
dlinkwit27 has no CT (Forum King) Join Date: Sep 2000 Posts: 13,236	arguments are as folows "expression, variable (which is in relation to), point at which to take the derivitive" ::Deviant Me::Last.fm::WhatPulse Stats::Folding @ Home

7th October 2004, 01:27	#12
k_rock923 \m/ (Forum King) Join Date: Jul 2003 Location: /bin/bash Posts: 7,850	i tried doing it the old fashioned way and then stopped because i forgot how to raise a binomial to the fourth Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway.

7th October 2004, 04:45	#13
Phyltre Forum King Join Date: Sep 2002 Posts: 2,751	This is why I never, never take any math course harder than Statistics 101.

7th October 2004, 05:10	#14
shakey_snake Forum Domo Join Date: Jan 2004 Location: Everyone, get over here for the picture! Posts: 4,313	put the expression argument in quotes or put the expression argument in Y-var and use that Y-Var in the d() expression. elevatorladyelevatorladyelevatorladyelevatorladyelevatorladylevitateme

7th October 2004, 22:13	#15
Kinetik* Forum Antagonist (Major Dude) Join Date: Jun 2002 Location: The Collective Rectum Posts: 1,154	I'll stick with College Algebra, where my TI-89 can do everything we're assigned to do in the class. Edit: If you ignore the fact that I just dropped out of college, that is. Procrastinators of the world unite!... Tomorrow!

8th October 2004, 01:47	#17
k_rock923 \m/ (Forum King) Join Date: Jul 2003 Location: /bin/bash Posts: 7,850	do you know what the actual answer is? .25x^4 let's see. power rule would make it 3(.25)x^3 so that gives .75x^3 and when you use .001, it gives you (.75)(.001^3)= 7.5 x 10^-10? um. . . Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway.

8th October 2004, 02:00	#18
Psythik Got his CT back and didn't pay $10 (Forum King) Join Date: Aug 2002 Location: Phoenix, AZ Posts: 3,583	And I thought sophmore geometry was confusing... This is a sig of some nature.

8th October 2004, 06:19	#19
Cognition Some Random Guy (Major Dude) Join Date: Mar 2003 Location: NZ Posts: 1,245	It's not a number that's really huge or really tiny is it? Cause that'd give an error.

8th October 2004, 15:02	#21
OutlawJim Confused (Major Dude) Join Date: Feb 2003 Location: Northern Ireland Posts: 1,017	i think my brain exploded from the complicatedness of the maths in this thread. thank god i never use it anyhow Nobby:I have ADD.... Germ:No shit, Nobby? Nobody would have ever guessed.

9th October 2004, 03:16	#22
squall14716 Senior Member Join Date: Oct 2002 Location: 127.0.0.1 Posts: 349	What exactly are you trying to do? Take the derivative of .25x^4 at 0.001? The derivative of .25x^4 is x^3. Plug in 0.001. The derivative of x^n is n(x)^(n-1).

9th October 2004, 03:26	#23
k_rock923 \m/ (Forum King) Join Date: Jul 2003 Location: /bin/bash Posts: 7,850	I see an error in my own calculations. I was tired. oops. Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway.

9th October 2004, 22:01	#25
squall14716 Senior Member Join Date: Oct 2002 Location: 127.0.0.1 Posts: 349	Post a trinomial then. I'm sure someone can factor it.

9th October 2004, 23:44	#26
k_rock923 \m/ (Forum King) Join Date: Jul 2003 Location: /bin/bash Posts: 7,850	x^2+2x+2 Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway.

9th October 2004, 23:57	#27
dlinkwit27 has no CT (Forum King) Join Date: Sep 2000 Posts: 13,236	you gotta use the quadratic equation: [-b +/- sqrt(b^2 - 4ac)] / (2a) I got (off the top of my head) (3+1i) * (-2-1i) as the factors. ::Deviant Me::Last.fm::WhatPulse Stats::Folding @ Home

10th October 2004, 00:11	#28
k_rock923 \m/ (Forum King) Join Date: Jul 2003 Location: /bin/bash Posts: 7,850	yea, but i meant you can't factor it into two real binomials. Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway.

10th October 2004, 04:16	#30
whiteflip Post Master General (Forum King) Join Date: Jun 2000 Location: Seattle, Now Las Vegas Posts: 6,032	the ti89 needs a backlight, so does my ti83. mia you are a trooper but you should try to use one of teaxa's instruments. they are quite good. I'm Back?

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