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Log & reciprocal functions

I can't find lo and reciprocal functions tabs.

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  • Anonymous Oct 27, 2008

     i dont not know where to access the reciprocal function on the TI-89


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There is no log (base 10) button on a TI-89. It's buried in the CATALOG as log(. As a shortcut, you can do ln(#)/ln(base), where # and base are replaced with what you want. For the inverse of a log, do the base raised to the part on the other side of the equals sign. So, log(x) = 2 would become 10^2 = x.

Posted on Oct 04, 2009

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It is much more enlightning to tell us what you want to do rather than talk about something that does not exist. And one thing that does not mean anything is that ellusive INVERSE key that everyone and his dog is looking for.
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Where is the inverse button on the casio fx-82ES

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I am not sure if there really is a question here. The cosecant function is defined as the reciprocal of the sine function : csc(x)=1/sin(x)
You can calculate two ways. [ ] is a single key press, [(-)] is the change sign key.

csc(-9.4946)=1[/][sin] [(-)] 9.4946[)] [EXE]

The other way is to just calculate sin(-9.4946). the result will be stored in ANS memory. At this time, if you press the key [x^-1] you are calculating the reciprocal of the result stored in ANS.

Both methods yield the same result.

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I have to take the secant of -1.2. I'm supposed to get a degree. I can't figure out the order to push buttons. PLEASE help!

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I depends on what you mean by INV.
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If you are thinking about the inverse of functions, then know that each function shares the same physical key as its inverse. For example to access the arcsine (the function inverse of sine) you press the [SHIFT] key before [SIN]. On the calculator you will notice that near the [SIN] key and to its left there is [SIN^-1].

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0.5=log Io/It find Io/It

A set a parentheses would sure help remove any ambiguities.
I assume your equation is 0.5 =log(lo/lt)
There is an equivalence

y=log(x) is equivalent to x=10^y

You can write
But 10^(log(x))=x, thus
10^(0.5)= lo/lt
and lo/lt=square root of 10
Here is a screen capture to convince you.


Hope it helps

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My log functions are wrong

It would help to know what you are trying to do or at least in what way you answers are wrong. I will do my best to guess right.

Ex: if you enter log(25) it gives you 2*log(5) and if you enter log(5) it echoes the same thing. If that is waht you get, it is easy to fix.
Press the Main icon at the bottom of the screen to open the calculator run screen. Unfold the first Menu to the left of Edit. Press Settings (first submenu) Press the/arrow and select Setup item, then Basic Format. Under Common tab you have the different formats: folder, display, angle, and Advanced. Put a check mark in the box to the left of Decimal Calculation an press Set to save configuration.

The other possibility is that you actived the 2D keyboard which gives you access to the 2d Function templates. You use these to calculate the log in arbitrary bases. Functions on this keyboard have a dark rectangle. If that is the source of your problem, use the stylus to select the mth keyboard.
Hope it helps.

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It does. For instance, to get the reciprocal of 4, enter the following sequence: 4 [1/x] (this last key to be found third row down, second black key in). The decimal 0.25 will appear as the result. Convert this, if you want, to the fraction 1/4 by pressing the yellow function key [2nd], then {F<>D] located bottom, far left. Hope that's what you wanted!

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