Question about Texas Instruments TI-30XA Calculator

# How do i find the negative log on a TI-30Xa - Texas Instruments TI-30XA Calculator

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### k24674

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• Texas Instru... Master

Hi,

Ex: calculate -log(15.32)

1. Calculate the log 15.32 [LOG] [=] result 1.185258765
2. Then press the change sign key (-) result -1.185258765
You can also try 15.32 [LOG] (-) [=]. Try to veriufy it on your calculator.

Here is a picture of the change sign Hope it helps

Posted on Dec 13, 2009

### Meredith Weigert

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If you are trying to calculate the [H+] concentration from pH, you take the number 10 and raise it to the negative pH.

for example, say the pH is 11. to solve [H+] concentration, use 10^-11 and that will give you your correct answer :)

Posted on Mar 08, 2018

### kakima

You compute the negative of a logarithm the same way you compute the negative of anything else. However, do you really mean the antilog (inverse logarithm)? Use 2ND [e^x] for the natural antilog, 2ND [10^x] for the common antilog.

For negative exponents, as well as negative anything, use the (-) key next to the decimal point. For your example, 1 EE (-) 6

Posted on Feb 25, 2010

### Anonymous

pH is minus (log to base 10) of the hydrogen ion activity of an aqueous solution, or (log to base 10) of (1/hydrogen ion activity)

To get the inverse log, i.e the hydrogen ion activity corresponding to a specified pH, simply enter the pH value and press

2nd
LOG
1/x

Posted on Jan 01, 2009

### Anonymous

SOURCE: Negative Exponent

1. Type in your base number

2. Press the EE button

3. Key in your exponent number.

4. Press the button on the bottom right hand side of the calculator that has both the positive and negative sign on it.

5. Press equals button.

Posted on Jul 30, 2008

### Anonymous

SOURCE: TI-30XA

Use the inverse log key sequences "2nd LN" or "2nd LOG" depending on whether you are using natural logs or logs to base 10

Posted on Dec 31, 2008

### Anonymous

I noticed that this calculator doesn't have a natural logarithm function as well. You can can always use the fact that
ln x = (log x) /log e or since log e is approximately .43429482
ln x = (log x)/.43429482. The greatest solution and it might be worth the 15 bucks or so to get a calculator with e^x and the natural logarithm function.

Posted on Mar 09, 2009

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× ## Related Questions:

### What is answer log5 (log25 2/5)=

The expression is ambiguous. You need to make it clear. Is it log_5 of log_25(2/5)? If that is the case then your expression is undefined because log_25(2/5) is negative (=-0.284661721) and a negative number cannot be inside a logarithm.
Be it as it may, the calculator does not calculate the log in bases other than 10 or e.
log_b(a)=log(a)/log(b)=ln(a)/ln(b)

Jan 18, 2013 | Texas Instruments TI-30XA Calculator

### How to fix error mesage on TI-30Xa. Every time I press LOG an error sign comes up. how do i fix this?

To take the log of a number, enter the number then press the LOG button, then the =. To take the log of a negative number, enter the negative number using the +/- key just to the right of the decimal point. To calculate the negative of a log, calculate the log and then negate it using +/-. To calculate the antilog (inverse logarithm), press 2nd then LOG.

Bear in mind that LOG is the common (base-10) logarithm. For the natural (base-e) logarithm, use the LN key to its right.

Nov 07, 2011 | Texas Instruments TI-30XA Calculator

### How do i solve 10^-4.80 on my TI-30XA

You would type in 10 [y^x] 4 [.] 80 [  ] [=] . This should make the 4.80 negative.

Mar 09, 2011 | Texas Instruments TI-30XA Calculator

### How do I use the LOG button? For instance to solve pH= -log [1.0 x 10-3]

The log function evaluates the logarithm of the expression in the display. To compute the negative log of 10x10^(-3), press 1 EE +/- 3 LOG +/- =

Nov 21, 2010 | Texas Instruments TI-30XA Calculator

### How do i make the log button negative?

Enter the number, then press the LOG button. Once result is displyed press the change sign key. If result is positive, it will become negative. If result is negative it will become positive. The Change sign key is the one with + -, located between the . and the = on the bottom row of keys.

Apr 01, 2010 | Texas Instruments TI-30XA Calculator

### I need to use a TI 30Xa to evaluate a Logarithm Log5 1/625 Not sure how to use the TI to do Log5

Use the relation log5(x) = log(x) / log(5) = ln(x) / ln(5)

LOG ( 1 / 625 ) / LOG 5 =

or

LN ( 1 / 625 ) / LN 5 =

Mar 11, 2010 | Texas Instruments TI-30XA Calculator

### What button do I use to find negative log on my TI-83 calculator...also how do I put in a negative exponent?? i.e 1*10 to the negative 6th .....

You compute the negative of a logarithm the same way you compute the negative of anything else. However, do you really mean the antilog (inverse logarithm)? Use 2ND [e^x] for the natural antilog, 2ND [10^x] for the common antilog.

For negative exponents, as well as negative anything, use the (-) key next to the decimal point. For your example, 1 EE (-) 6

Feb 25, 2010 | Texas Instruments TI-30XA Calculator

### How to use antilog?

Hello,

As you well know the pH is the negative of the log in base 10 of the H+/H3O+ ion concentration. If we use [H+] to represent that concentration, then pH=-log[H+].
To obtain the [H+] you need to calculate the antilog. You write the definition in the form log[H+] =-pH and then calculate 10 to the power of each member. The equality remains valid as both members are treated similarly. Thus
10^( log[H+] ) = 10^(-pH)
Since raising 10 to a power is the inverse function of taking the log in base 10, 10^(log(x))=log(10^(x)) = x (they are inverse of one another), you are left with

[H+]=10^(-pH)

Your calculator has a function [10 to x] accessed by pressing the [2nd] function key. To use it you must enter the negative value of the pH, press the [2nd] function key then the [10 to x], then the = key to get the result (concentration)
Exemple: let the pH=5.5, what is the H+ concentration?
With [(-)] being the change sign key, then
[H+]:[ (-) ] 5.5 [2nd][10 to x] [=]
The result is 0.000003162 or 3.16 x 10^(-6)

Hope it helps.

Dec 07, 2009 | Texas Instruments TI-30XA Calculator

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