Log to the Base (a) on TI-89 | Every Step Calculus Video
Raw Transcript
This is the video on log to the base whatever and it’s pretty easy if you’re always into it but it’s complicated if you look at it each each time and say what the heck’s going on there. So it’s best to have it programmed and just forget it put the stuff in and forget it. Um, turn the calculator on here, I’m gonna get out of this program here by pressing ON,
ESCAPE and HOME and I’m gonna clear the entry line there. And I want to clear the screen up here too so I’ll press F1, 8 on that Get used to those they are always necessary and all very useful, you have to enter index eight in here to get the main menu so I’ll press second alpha second here Alpha makes it dark show your showing your entering letters i_n_d_e_x and then you have to go Alpha again to get in numbers again in parentheses and other functions for numbers, ok so you press Enter and your into my menu. This one’s on logs, were going to scroll up here… many things go to get quotient rule quadratic formula whatever you need in here limits, path of an object, that’s a beautiful program shows you everything possible, I give you a sheet that shows you the whole outline what’s on the calculator so you can really look at it on one 8×10 sheet see exactly what youre going after here such a small screen on the titanium anyways we’re gonna go.. it’s all alphabetical. So we got natural log here and we got log of x you know log of base a different base we’re going to scroll down to there there’s a number before it or letter, there’s numbers up here there’s letters here if you want to go to if you want to do a quick and you knew the letter you can just pull Alpha find the letter on here and you would go to that that particular program and so we’re gonna go log problems here and we have to put in logs and again we have to go second and Alpha notice there’s no darkness here so we’re not doing it yet. We’re not into the letters now we are and we need to push, put it in l_o_g and then we need to put the base in there so lets go to base 8 and then we have to go. I have parentheses so that we’re going to put in we’re gonna solve for 5 times x minus one and closed parentheses and we have to make it equal, if you didn’t put any didn’t make any mistakes up here for instance let’s try to enter it now with um.. it says must be an equation with an equal sign so then it goes back now to the program and then you can um you can Press the right cursor here goes to the right side of the program you can put the equal sign in there notice it didn’t put the equal sign in so I have to press Alpha again and then the equal sign, keep track of that and let’s say it equals to 3 okay then press Enter here, notice here we have the log of 8 f of x which equals three and we say that’s what we entered, cool give you the choice of finding x or the exponential form if you went to the exponential form right now it wouldn’t find it because of x and it tells you that you you can’t you must solve for x first so were gonna solve for x here first or sometimes in tests that’s to only thing your doing here’s the answer…8 to the radical 3 equals the inside 5x-1 5x minus 1, equals 512, x equals 513 over 5, that’s the correct answer if you want to get an approximate answer you divide 5 into 513 but this is the exact answer pretty neat huh? Go to my website EveryStepCaluclus.com. Enjoy my programs.
log a(x) Evaluate on the TI-89 App | Every Step Calculus Video
Raw Transcript
I’m going to demonstrate the log to a base x or rather the base you want on the titanium calculator, these are particularly difficult to remember them from months and months from week to week and I program them, so they are not easy but it will be easy if you studied every second of your life like a professor does. So let’s get started, we are going to press, put my code in to get to my menu, second alpha, you can see the black mark here on your screen which tell you, you can do letters and we are going to put in “index”, we have to press alpha again to get to the second numbers 8 and close parenthesis, it’s all in the instructions that I send you when you purchase my programs. And then we want to scroll down here, notice all the things you can do, all the different things in the menu, all in alphabetical order, we’re going to go down to log of x here and we are going to press enter and we’re going to get into log problems. I’m proud of this program because, well let’s do evaluate for instance, you can press the number before the program or scroll down to it, press the number, give you some examples so you’ll know what to enter and we are going to put in, you’ve got to press alpha before you add anything into these lines here and you need to put the log, the word log in there, let’s see if it happens, if it doesn’t happen that’s number 4 so we have to press the alpha maybe second alpha again and then put in log and then alpha, we are going to put in a number, so we are going to do log to the base 2 and let’s do 1 divided by 8 or 1/8 and it shows you what you’ve entered, you can change it or accept it, I say it’s ok, press number 1, you know it was supposed to take you right down on your paper and this is the way it is, you take the same base on both sides and so am taking log 2 or base 2 to the x here and then we are going to do base 2 to the 8 which is 3 and then because this is denominator you have to bring it to the numerator so it will make an exponent, so its 2 to the minus 3 and if they have the same base then the exponents are going to equal, so here we have X equals a minus 3. Let’s do another one. Let’s take log of… on the internet, people have said how do you do by hand, step by step for instance log 3 to the 15 and sometimes the answer is you can’t, you need the log tables or you need the calculator to do it, you cannot do things by hand, everything by hand, so even though they try to tell you that you can, show you different things, the real answer is you can’t do it by hand, you have to use a calculator and that’s the reason that Napier did the log tables in the first place to eliminate that. So let’s do log to the … lets go and put in log Alpha 3(15). You can see log3(15), I say it’s ok again I’m going to go one. Notice I told you that you have to use the calculator or table of logs to solve this and so the way you do that is you add the X=log3(15) and then you convert it to exponential form, 3 to the X equals 15 that’s the question but then you divide log of 15 by log of 3, and log of 15 in the calculator is 2.71, log of 3 is 1.1, so the answer is 2.465, so 3 to the 2.465 is equal to 15 and you can go back to another problem, you can also go back to the main menu but I’ll save that for another video. everystepcalculus.com, enjoy my programs they’re great.