Solve function

[Amanda Land]

We are currently studying absolute value equations and after teaching the lesson I always like to go back and teach them any calculator shortcuts there are to check their work or for my low level kids, calculator ways to get the answer.  Why or how does the regular Nspire come up the answer it does when you do the solve function for one of these problems?  I know the CAS gives both answers but the regular handheld only gives one...basically i am wondering why it gives one over the other and if you guys know of anyway to get the other.....thanks!

On Dec 14, 2011 7:11 AM, "Andy Kemp" <an...@kemp.co> wrote:

Indeed - I've often wondered why we use the fix/float concepts rather than the more standard decimal places and significant figures concepts anyway...

On Wed, Dec 14, 2011 at 12:54 PM, Sean Bird <covena...@gmail.com> wrote:

I'm an advocate of Float.
The answer you got was due to Float 6 - only giving 6 digits.
If they up arrowed once and press Enter, then pretty much all the digits the Nspire knows would be revealed.

In the summer assignment I've given my Calculus students (see Primer at the top of http://covenantchristian.org/bird/Nspire.html ) I have them change the settings to Float.

There are a few assignments that I give that Float 6 or Fix 4, as in your example would not result in a sufficient answer. E.g. 0.000 002 is not counted correct when the students are entering their answer in Webassign and the answer is more precisely 0.000 00178.

That does make me wonder, why is the default Float.
- Sean Bird
Covenant Christian High School
Indianapolis, IN

On Wed, Dec 14, 2011 at 7:12 AM, <CHa...@cattlv.wnyric.org> wrote:

Hello everyone-

Something that I found really odd happened yesterday.  My students were using the TInspires (on a calculator page) to just multiply 1995 times 111.5

Every single calculator that was in use, gave the wrong answer.  Instead of 222442.5 these calculators gave the rounded form 222443.

I don't understand why.  A colleague of mine told me NEVER to leave the calculator on "float" or even the default value of "float 6".  He says that he has all of his students change the settings to "fix 4".

My questions are:  Is there some other setting that is not properly configured on my TInspires that would cause that automatic rounding?  Why would the default setting allow for automatic rounding rather than an exact answer?

thanks for you help


Cathy Haynes
Algebra Teacher
Cattaraugus Little Valley Central School
25 N Franklin Street
Cattaraugus, NY  14719

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[John Hanna]

Using nSolve does a ‘sort-of’ bisection method or Newton’s method search for a solution, hence only one answer at a time.

 

You could restrict the solution space with:

            nSolve(abs(x) = 2, x) | x<0

or

            nSolve(x^3-2x=1,x) | -1<x<0

 

All the best,

     John Hanna

     jeh...@optonline.net

     www.johnhanna.us

     T³ - Teachers Teaching with Technology

     "A cowchip is paradise to a fly."

 

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[epi van winsen]

You can also use some more parameters with nSolve.

nSolve(abs(x)=2,x,0) gives a solution greater then 0.

Epi van Winsen

[epi van winsen]

I don't see the screen in my last response.

So here are the commands:

nSolve(x^(3)-2*x=1,x)|−1<x<0  does the same as:

nSolve(x^(3)-2*x=1,x,−1,0)

nSolve(abs(x)=2,x)|x<0  does the same as:

nSolve(abs(x)=2,x,−10^(99),0)

nSolve(abs(x)=2,x,0) restricts to x>0

Epi

Op 14 dec. 2011, om 14:55 heeft John Hanna het volgende geschreven:

[John Losse]

Cathy might be able to use the zeros command instead of nSolve.  The output is a list.

[Andy Kemp]

Unfortunately Zeros is also a CAS function so isn't available on the Numeric Nspire

[alcoonslists]

I assume there is no way to do the following except to use lists and spreadsheets but I thought I would ask:

Without going to Lists & Spreadsheets:

Given a function, say f1(x)=x^2, a table will display a column for x and a column for f1(x). A student also wanted to display the change between successive inputs in the next column, i.e. f1(x)-f1(x-1).

Thanks,

Al

[Scott Lockhart]

I'm not quite sure exactly what you mean by the question, but does this screen shot help to answer the question that it DOESN'T have to be on an L&S page?

[Andy Kemp]

You can't do it directly on the table view but from list & Spreadsheets you can use the deltaList function! (just type deltalist(column))

 

[John Hanna]

In the SS:

          Col A formula: seq(x, x, 1, 10, .25) (or whatever)

          Col B formula: f1(a[ ])

          Col C formula: deltalist(b[ ])

 

Notes:

          The formulas go in the grey cells at the top of the columns.

          You don’t need the [ ]'s if there are no variables by those names: the sw will assume you mean cols and place them there for you.

 

Busy day on this list, eh? Better than TICARES!!

     John Hanna

     jeh...@optonline.net

     www.johnhanna.us

     T3 - Teachers Teaching with Technology

     "A cowchip is paradise to a fly."

 

 

-----Original Message-----
From: tins...@googlegroups.com [mailto:tins...@googlegroups.com] On Behalf Of alcoonslists
Sent: Wednesday, December 14, 2011 10:48 AM
To: tins...@googlegroups.com

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[John Hanna]

Sorry, I did not see " Without going to Lists & Spreadsheets:"
Why not??

So...
On the Graph page,
Define f2(x) = f1(x)-f1(x-1) and press [enter]
Better yet, insert a slider for d and make it
f2(x) = f1(x)-f1(x-d)

From the graph, press ctrl-T for a table. (but the Table is just a different
view of the SS!)

John Hanna
jeh...@optonline.net
www.johnhanna.us
T3 - Teachers Teaching with Technology
"A cowchip is paradise to a fly."

-----Original Message-----
From: tins...@googlegroups.com [mailto:tins...@googlegroups.com] On Behalf
Of alcoonslists
Sent: Wednesday, December 14, 2011 10:48 AM
To: tins...@googlegroups.com

Thanks,

Al

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[alcoonslists]

Hi John,

Just wanted to see if we could do it on a graph/table page since that is where the question came up at the time. Every question I ask helps me learn a great deal.

Al

Al
-------------------------
Albert Coons
al_c...@bbns.org
Buckingham Browne & Nichols School
Gerry's Landing Road
Cambridge, MA 02138
(617) 800-2264

AP Statistics Web Site: www.bbn-school.org/us/math/ap_stats

[alcoonslists]

Guess I should have said:  Doing it in a table (command-T).  Sorry.

Al

On Dec 14, 2011, at 10:56 AM, Scott Lockhart wrote:

I'm not quite sure exactly what you mean by the question, but does this screen shot help to answer the question that it DOESN'T have to be on an L&S page?

<image.png>

On Wed, Dec 14, 2011 at 7:47 AM, alcoonslists <alcoon...@verizon.net> wrote:

I assume there is no way to do the following except to use lists and spreadsheets but I thought I would ask:

Without going to Lists & Spreadsheets:

Given a function, say f1(x)=x^2, a table will display a column for x and a column for f1(x).  A student also wanted to display the change between successive inputs in the next column, i.e. f1(x)-f1(x-1).

Thanks,

Al

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[alcoonslists]

OK. I give up. HH is in radian measure, and I want to force sin(30) to be computed in degrees. Guidebook say press CTRL ' after inputting the angle measure but I get an error message on the HH. I am using the ' from the "?! >" key. Probably is some other character. Suggestions?

Thanks,

Al

[Dennis Donovan]

Ctrl-' is the keyboard command to use in the teacher/student software to get a degree symbol.  On the ?!> key on the handheld there is a degree symbol (to the left of the ' symbol), use that.

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From: alcoonslists <alcoon...@verizon.net>
To: tins...@googlegroups.com
Sent: Wednesday, February 8, 2012 10:15 AM
Subject: [tinspire] forcing degrees

OK.  I give up.  HH is in radian measure, and I want to force sin(30) to be computed in degrees.  Guidebook say press CTRL ' after inputting the angle measure but I get an error message on the HH.  I am using the ' from the "?! >" key.  Probably is some other character.  Suggestions?

Thanks,

Al

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[Jessica Kachur]

are you in a document or on the scratchpad?

If you are on the scratchpad, the default is radians.  When you change the settings to degrees, you have to tell the handheld to make that the default so that it will change the scratchpad setting to degrees

 

Jess Kachur
Mathematics Teacher, Whitnall High School
T3 Regional Instructor
Muka, CGC, TDI, Retired, CL2, CL3-F, CL3-S, CL3-H, TN-O, WV-N
and
C-ATCH Jibay, Sandy Acres lil' Phantom, AD, AJ, SSA, SG, SS, SR, NA, NAJ, TDI, CGC, ChST, ChSN, ChFH

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To: tins...@googlegroups.com
Cc:
Sent: Wednesday, February 8, 2012 9:15 AM
Subject: [tinspire] forcing degrees

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[alcoonslists]

Thanks.

Just in case I am not the only one learning this feature:

The same degree symbol is available in ctrl-catalog.

To force degrees into radians the little "r" in ctrl-catalog does the trick.

Al

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[Marc Garneau]

The radian character is also available using the pi-key.

[alcoonslists]

OK but I have to wonder what the logic was on that.  Why would it not be on the "? !" key with the degree symbol?  Or visa-a-versa.  There is an empty space on both.

Thanks,

Al

[John Hanna]

Yep… strange layout indeed. I’d like to see more redundancy.

 

     John Hanna

     jeh...@optonline.net

     www.johnhanna.us

     T³ - Teachers Teaching with Technology

     "the future isn't what it used to be."

 

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[Travis Bower]

I justified it in my mind to avoid accidental keypress.  [which is pretty weak since that argument fails with all the Trig functions in their own pop-out]
My mnemonic is pi and radian go together.
Why not have both in both?

[Marc Garneau]

The nice thing about generic keys is that a software update could make the suggested improvement.  

Marc