The Student Room Group
Original post by Revisionguide101
Hi
When i try integrating on the fx 991es calculator:

4x^1/3 + 4x

between 0 and 8 x values

it takes ages to produce a value on the calculator. 7 minutes! can Someone try this on their calulcator to see if they have the same problem? thanks


Didn't take 7 minutes, but it got the answer of 176. Besides, it's not that hard of a problem to do by hand and calculate single values to the 4/3 using the calc. Much faster then...
Original post by Revisionguide101
Hi
When i try integrating on the fx 991es calculator:

4x^1/3 + 4x

between 0 and 8 x values

it takes ages to produce a value on the calculator. 7 minutes! can Someone try this on their calulcator to see if they have the same problem? thanks


Don't try taking that calculator to your exam, my friend was disqualified for using that calculator on his exam. Not worth the risk if you're intentionally taking it in there because of its differentiation capabilities.
Original post by Revisionguide101
Hi
When i try integrating on the fx 991es calculator:

4x^1/3 + 4x

between 0 and 8 x values

it takes ages to produce a value on the calculator. 7 minutes! can Someone try this on their calulcator to see if they have the same problem? thanks


Why do you want to use your calculator to integrate for? Are you just checking your answer?
Original post by RoyalSheepy
Don't try taking that calculator to your exam, my friend was disqualified for using that calculator on his exam. Not worth the risk if you're intentionally taking it in there because of its differentiation capabilities.

That calculator is allowed and is recommended for A-Level maths as it doesn't do Symbolic differentiation or integration, it just gives you the answer to an integration/differentiation between 2 points which doesn't get you marks in the exam.
Original post by Logic4Life
That calculator is allowed and is recommended for A-Level maths as it doesn't do Symbolic differentiation or integration, it just gives you the answer to an integration/differentiation between 2 points which doesn't get you marks in the exam.




My exam board, the WJEC, definitely does not permit of this model calculator. I assume it'd probably be the same for other exam boards...
Depends on the exam board. AQA allows it. I used it.

It takes a while for my one.
Original post by RoyalSheepy
My exam board, the WJEC, definitely does not permit of this model calculator. I assume it'd probably be the same for other exam boards...


OCR allows it and so does AQA so I don't know
Woah I have the fx991EX classwiz and it took 30 seconds...it's never taken that long before...
Original post by Logic4Life
OCR allows it and so does AQA so I don't know


Hmm, not sure then. If you're definitely sure then it must be; but I assumed if one exam board bans it the rest should technically do the same...
Original post by RDKGames
Didn't take 7 minutes, but it got the answer of 176. Besides, it's not that hard of a problem to do by hand and calculate single values to the 4/3 using the calc. Much faster then...


Yeh i just use it to check answers in exams
Original post by Philip-flop
Why do you want to use your calculator to integrate for? Are you just checking your answer?


yeah
Reply 12
As others have said, it is definitely OK to use this calculator for AQA, and a quick glance over the other specifications indicate that it should be OK for them too - including WJEC.

I often find that some teachers think calculators like this are not allowed when they are. It is a great timesaver to check the values of definite integrals, because if they agree with your value, you don't have to waste time checking them. Similarly for other things which you need to show working for, but you can check if you are right, like simultaneous equations and roots of quadtatics and cubics.
Mine has taken 2minutes and counting
Reply 14
3 minutes 20 seconds on my fx-991ES, around 40 seconds on my fx-991EX. I've seen it come up with the answers much quicker for integrals that look far more complicated at a glance. I've never looked into the theory behind the method it uses to do these integrals - there must be something about this one that slows down the output compared to other problems.
Reply 15
Yes.
I get a similar problem in my fs-991EX, but with integrating "50x^1/2 + 20x^2 - x^3", with limits of 20 and 0
Original post by Chinook7532
I get a similar problem in my fs-991EX, but with integrating "50x^1/2 + 20x^2 - x^3", with limits of 20 and 0


Its an old thread, but Id guess its because the derivative of x^(1/2) is infintie at 0. You could test by using 1 as the lower limit and/or replacing the x^(1/2) with x. Neither are a solution to evaulate this definite integral, but some iterative numerical algorithms run into problems in such cases, and its an easy thing to test/be aware of.