TI-89 help - UPDATE - cube roots needed

jeddy lee

How do you turn off the Auto Radicals? My wife bought one used from the web and it works fine, but it displays answers only in radicals and fractions, and we can't figure out how to give us the decimals even if we want it. I skipped the whole scientific calculator thing in school, but she definately needs it.

Hahnsoo1

The official TI-89 manual is available in PDF form here:
http://education.ti.com/downloads/guidebooks/graphing/89ti/TI89TitaniumGuidebook_Part2_EN.pdf

Also, there's a TI-89 website out there:
http://ti-89.org/faq.html

Apparently, you'll have to go to the MODE dialog box, page 2, and select DEC as your Base.

Also, you can turn Pretty Print On and Off, which may be part of your problem.

The other option is turning Exact/Approx to Auto or to Approx. Exact retains the original formatting to reduce rounding errors, but it's not helpful if you need decimal answers.

Read p 166-170 in the manual (first link) for more options.

ProPatriaMori

Hahnsoo1 wrote: »

The other option is turning Exact/Approx to Auto or to Approx. Exact retains the original formatting to reduce rounding errors, but it's not helpful if you need decimal answers.

THIS.

Or, if you want to generally retain fractions and radicals (to get exact answers) but only occasionally want decimals, you can hit the green button then the enter key (I think the relevant label on the calculator is an approx. equal sign)

finalflight89

I've got a TI-89 and I've always just placed a decimal point after any whole number in the calculation, and it will give you the decimal approximation rather than the exact value. No settings to mess with!

.kbf?

Theres an option under mode with the three settings for this


Exact -> always gives exact answer. If it can't it will just output the input

Approximate -> always gives decimal approximation

Auto -> always gives exact answer if it can. If it can't it will give the decimal approximate

edit: woops already covered

jeddy lee

Thanks guys.

jeddy lee

I can't find in the manuals how to do a cube root of a number other than doing 27^(1/3) which frankly is kind of a pain in the ass. I know my iPhone has a x root of y button, I'd figure a scientific calculator would too. Unfortunately she can't bring my phone into a test with her, lest I text her the answers.

ProPatriaMori

well, there's root(number, order). Which isn't less of a pain in the ass, really. It's more of a pain in the ass. It is easier to read in the pretty print, though.

I also don't see anything in particular in catalog.

How is ^(1/3) a pain in the ass again? Honestly it seems like the right way to do it, to me. There are only so many buttons you can have on the face of a calculator, so the more flexibility you get (like with ^) the better.

Dark_Side

ProPatriaMori wrote: »

well, there's root(number, order). Which isn't less of a pain in the ass, really. It's more of a pain in the ass. It is easier to read in the pretty print, though.

I also don't see anything in particular in catalog.

How is ^(1/3) a pain in the ass again? Honestly it seems like the right way to do it, to me. There are only so many buttons you can have on the face of a calculator, so the more flexibility you get (like with ^) the better.

Yeah, stick with ^(1/3), using a function to do it will be a pain in the butt.

.kbf?

correct me if i'm wrong but isn't it the same amount of button presses either way?

edit: it's 5 for the ^ method. Assuming the xrooty button is on 2nd i guess it's be 4?

Dark_Side

I can't even remember how to find the function to do it, but I know I just prefer doing it the other way because you can do it all off of keys on the calc without having to use the shift or dig into menus.