Ex:  Evaluate Natural Logarithms on the Calculator

Ex: Evaluate Natural Logarithms on the Calculator


– WE WANT TO EVALUATE
THE GIVEN LOGARITHMS, AND THEN WRITE
AN EXPONENTIAL EQUATION TO SHOW THE MEANING
OF THE VALUE. NOTICE BOTH OF THESE
ARE NATURAL LOGARITHMS, WHICH MEANS BOTH OF THESE
ARE LOG BASE E. AND JUST TO REMIND US OF THIS, LET’S GO AHEAD AND PUT
THE LITTLE E HERE AND HERE. THE GOOD NEWS
IS MOST CALCULATORS CONTAIN A COMMON LOG BUTTON AS
WELL AS A NATURAL LOG BUTTON. SO IF WE GO TO THE CALCULATOR,
TO EVALUATE NATURAL LOG 7, WE COULD JUST PRESS LN, 7,
CLOSE PARENTHESIS, AND PRESS ENTER. WE DO WANT TO ROUND
TO THE HUNDREDTHS, SO THIS WILL BE APPROXIMATELY
1.95.   TO HELP US TO UNDERSTAND
THE MEANING OF THIS, WE NOW WANT TO WRITE THIS
LOG EQUATION AS AN EXPONENTIAL EQUATION. AND THERE ARE SOME NOTES HERE
TO HELP US IF WE NEED IT. BUT E WOULD BE THE BASE, THE EXPONENT WOULD BE
APPROXIMATELY 1.95, AND THIS WOULD BE
APPROXIMATELY EQUAL TO THE NUMBER 7. WE’RE SAYING APPROXIMATELY
BECAUSE WE DID ROUND THIS. AGAIN, E TO THE 1.95 WOULD BE
=TO APPROXIMATELY 7. WE CAN GO AHEAD AND VERIFY THIS
ON THE CALCULATOR AS WELL. IF WE PRESS SECOND NATURAL LOG IT’LL BRING UP E RAISED TO THE
POWER OF 1.95, PRESS ENTER. NOTICE HOW IT IS
APPROXIMATELY 7. IT IS A LITTLE BIT LARGER
BECAUSE WE DID ROUND UP WHEN ROUNDING
TO THE HUNDREDTHS. FOR OUR SECOND LOGARITHM,
WE’LL TYPE IN LN, 0.25, CLOSE PARENTHESIS, ENTER. AND AGAIN, ROUNDING
TO THE HUNDREDTHS WE’D HAVE APPROXIMATELY -1.39. AND NOW TO WRITE
THE EXPONENTIAL EQUATION, THE BASE IS E,
THE EXPONENT IS -1.39, AND THIS SHOULD BE
APPROXIMATELY EQUAL TO THE NUMBER 0.25. LET’S GO AHEAD
AND VERIFY THIS AS WELL. SO SECOND LN, -1.39, CLOSE
PARENTHESIS, PRESS ENTER. AND NOTICE HOW THE VALUE
IS APPROXIMATELY 0.25. AGAIN, E RAISED TO THE POWER
OF -1.39 IS APPROXIMATELY 0.25.  

3 thoughts to “Ex: Evaluate Natural Logarithms on the Calculator”

  1. You are so awesome, just found your video library…. WONDERFUL!!! Thank you soo much, love the videos, very easy to understand. God Bless You. Eboni

  2. my TI-84 Plus CE calculator will calculate the answer when using ln, but when I enter e^-1.39 it will not solve it. What settings do I need to change to have it work on both parts of this problem? THANKS!

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