Help! Equation doesn't compute

[McEwan25]

Hi all,

I've just enrolled on a mostly self-study course of mathematics as an adult (who failed maths at school) and I'm doing a chapter to get to grips with just using a scientific calculator and I'm pulling my hair out already. I have been stumped on an example equation for the last hour just re-entering it into my calculator to no avail.


I am wondering if someone here can explain this to me as I'm anxious as **** now, fearing I'll never learn anything if I can't even get the first equation into the calculator properly.

The example in the book has been attached as a photo. My problem is when I enter that equation exactly as laid out in the book I get a syntax error, I have tried so many combinations to try and get it to work like putting brackets around the sets of numbers, then taking them away, then doing the entire equation by using the fraction button on the calculator and so o and so forth.....

Nothing is working and now I feel completely hopeless ?

 

[Dr.Peterson]

You're saying that you hit exactly the keys shown, and the calculator complained? Don't try changing what you enter (yet); let's figure out why the instructions seem to be wrong.

My first question is, what exact model of calculator are you using, and what model are these instructions intended for? If they don't match, there could be a problem! A picture of your calculator at the point where it displays the error, or just before that, might be helpful.

I can see some possible specific issues (e.g. an extra parenthesis or a separate negation button), but until I know the model and see your calculator, I can't be sure.

All I know for sure is that your calculator isn't the same as mine, which doesn't have an x³ button at all.

 

[McEwan25]

1. I'm using a 'Casio fx-85GT PLUS.'

2. The textbook doesn't specify a model, it just states some functions which aren't exactly the same buttons as the ones shown on my calculator - but I have worked out what they are thanks to Google.

I've attached an image of the equation as I am typing it into the calculator and the error code.

Thank you for taking a look into this for me.

 

[Dr.Peterson]

1. I'm using a 'Casio fx-85GT PLUS.'

2. The textbook doesn't specify a model, it just states some functions which aren't exactly the same buttons as the ones shown on my calculator - but I have worked out what they are thanks to Google.

I've attached an image of the equation as I am typing it into the calculator and the error code.

Thank you for taking a look into this for me.

Thanks, that's perfect.

The problem is one of the two I'd suspected. The book shows a single close-parenthesis after the 16, which is intended to close off the numerator; some calculators automatically insert an open parenthesis when you hit the square root button, forcing you to enter an extra close-parenthesis after your radicand in order to exit the radical. It looks like yours took that parenthesis that way, but also displayed it inside the radical, so I suspect you are supposed to use a right arrow or something to exit the radical, and then you can type that one parenthesis you were told to type.

The other possible issue was that they seem to show the ordinary "subtract", -, button after the EXP, where many calculators want you to use a special "negate", (-), button. I can't be sure whether your calculator just ignored the difference here, but would give you trouble elsewhere, or doesn't need the "negate". That may be worth being aware of.

This is one reason it is very hard to teach calculator usage. Unless you require a specific kind of calculator, it is impossible to teach something the same way for every student. What they should really be teaching you is not "use this sequence of keystrokes", but "know how your calculator works, and watch the screen to see that it is doing what you want it to do".

In particular, the important lesson in this problem is that a fraction bar has to be handled by putting the numerator and denominator in parentheses, with a division between: ( ... ) [MATH]\div[/MATH] ( ... ). Looking at your screen in the first image, you should see that the close-parenthesis for the numerator is missing, and then work out a way to get it in there (and not have the extra one inside).

The other important lesson is, this is not your fault, and you aren't "bad at math". Your anxiety is natural when you are, in effect, being taught in one language and having to do your work in another (your calculator's). You should probably ignore the keystrokes they show, at least in detail, and learn your calculator from its manual or other materials from Casio.

 

[McEwan25]

I have set the textbook aside for today but will follow up with your advice tomorrow and let you know if it works (I'm sure it will).

Thank you very much for the prompt help. I'll be posting again on the forum in the coming months no doubt.

Out of curiosity are you aware of any notable free online resources that I could use to supplement the textbook?

It will all be high school level Mathematics . . .

 

[McEwan25]

Hey Dr. Peterson,

I followed your advice and managed to get it working. Thank you so much as now I feel confident enough to crack on with the rest.

I'll keep using my calculator for now, out of curiosity is there any particular brands/calculator models you find easiest to use for a beginner?