TI-89 Question: What is the proper way to do fractions?

[Nocturnal]

I was told to use parentheses around the fraction but sometimes when I do this is messes up the fraction when I add, sub, multiply, and divide. What's the proper way?

 

[petery83]

i usually don't use parentheses at all, and just let the order of operations take care of it

 

[RaynorWolfcastle]

if it's anything like the TI-83 I used in high-school a few years back, there's a "FRAC" key that just converts the decimal to a fraction. so you just do everything as a decimal and hit ans>frac at teh end and get a fraction

 

[Nocturnal]

The TI-89 actually doesn't have that lol. I think I should sell this and get an 83.

 

[agnitrate]

What are you trying to do with them? Just use ()s if you need to for your order of operations. The 89 kicks the 83's ass, don't even think about selling it.

If you want to approximate the fraction it displays, hit the green diamond (below 2nd) and then enter and it will make it a decimal.

-silver

 

[TuxDave]

Originally posted by: Nocturnal
I was told to use parentheses around the fraction but sometimes when I do this is messes up the fraction when I add, sub, multiply, and divide. What's the proper way?

How can it possible mess up?

(a/b)*(c/d)
(a/b)+(c/d)
(a/b)-(c/d)
(a/b)/(c/d)

All works for me.

 

[KingNothing]

The TI-89 has a mode in the options to output answers as either fractions or decimals all the time. I leave mine set in "fraction" mode and hit the green diamond + Enter when I want to see a decimal answer.

Parentheses are there to either change order of operation or make it more clear to you what's happening when. It will never "mess up a fraction" unless you do something boneheaded with them, like 3 + (4/5) when you mean (3 + 4) / 5.

Keep your TI-89 and learn to use it, geez. It's light years better than an -83.

 

[Gunther]

I use parentheses around fractions all the time on my 89 and it works fine for me. I do it the way dave does it ie (3+2)/(2+4). Don't trade it for a 83, there is no comparison. Whenever I use a 83 it feels like I went from a 3ghz machine with xp to a 486 with dos 🙁

 

[beer]

You don't need the frac button.

In Mode, you have the options of Approximate, Exact, or Auto

Using Approx will give you decimal approximations.
Using Exact will give you fractional or sybolic answers. Sometimes, they are insanely complicated though....they will give you your answer in terms of fractions, trig functions, contants such as pi, etc.
Auto will give you the 'best' answer. It will keep the fractions but do away with giving you your answer in terms of trig functions.

In no way is an 83 better than an 89. Also, the green diamond + enter gives you it in decimal, as has been mentioned.