TI89 question

Discus: SAT/ACT Tests and Test Preparation: July 2004 Archive: TI89 question
 By Best_Wr (Best_Wr) on Tuesday, July 20, 2004 - 04:49 pm: Edit

i have TI 89 titanium, and it doesn't have log or e^ on the keypad (it does have it in catalog but it takes too long to get there every time).
does regular TI 89 have these keys? Do you know how to get to log and e^ quickly in 89 titanium?

 By Joshjmgs (Joshjmgs) on Tuesday, July 20, 2004 - 04:57 pm: Edit

For log, it's easy to type in l-o-g, or just use natural log, which is two buttons below in the big yellow one with a grey diamond in the middle of it.
For e, it is two buttons below the big yellow one. You need to press the yellow button then X to use the e^ though.

 By Averagemathgeek (Averagemathgeek) on Tuesday, July 20, 2004 - 05:01 pm: Edit

The regular 89 does have an e^ button. You press [diamond][X] to use it. You could always just type in "log" to use the function, or you could use "ln" and convert it to base 10.

Edit: Looks like someone beat me to the first response (and put more useful info). Laughing out loud at myself.

 By Best_Wr (Best_Wr) on Wednesday, July 21, 2004 - 01:42 am: Edit

oh, so regular TI 89 doesn't have log... ok.
thanks tho.
has anyone used "SAT II Math with TI?"

 By Best_Wr (Best_Wr) on Wednesday, July 21, 2004 - 01:43 am: Edit

planning to take IIC, with 89. the book i mentioned above shows techniques with 83, but would that be OK? (i don't think many used the book cuz it came out in april...)

 By Nike1800 (Nike1800) on Wednesday, July 21, 2004 - 05:54 pm: Edit

IT does have log.
If you press [catalog], then alpha->l, and scroll down a bit, you'll find the log() function. To use it, put the number that you want to find the log of, then close the parentheses.
(Ex. log of 1000 -

log(1000), [enter]

It should then display 3
)

 By Abogachkov (Abogachkov) on Friday, July 23, 2004 - 12:41 am: Edit

The Ti-89 is such a powerful tool for the IIc test. For many of the questions, (involving the knowledge of ln, powers, etc.), you can just type in an entire equation, and it solves it! also, For the TI-89, you are able to create your own functions. press [2nD] then [HOME] then [F2] then [6] - this asks you to define f(x), so rename f(x) to be whatever you want like "L(x)" for log. so the screen should say "Define L(x) = log(x)" - you press enter, and the calculator stores that as a function.

 By Best_Wr (Best_Wr) on Friday, July 23, 2004 - 01:10 pm: Edit

so why is that "define" thing useful?

 By Abogachkov (Abogachkov) on Friday, July 23, 2004 - 01:15 pm: Edit

instead of typing in log(x) you can just type in L(x). Also, you can define more complex functions. You can define a quadratic formula function quad(a,b,c) = -b+sqrt(b^2 - 4ac)/2a....

 By Scorp (Scorp) on Friday, July 23, 2004 - 04:58 pm: Edit

quad formula: just do solve(ax^2+bx+c=0,x) and hit enter.