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# HP Prime showing square roots as fractions

03-26-2019 05:44 PM

If I enter a square root, it is showing as fractions. For example, it shows square root of 5 as 3940598/1762289 as well as 3010349/1346269. Is there anyway that I can make it so that the calculator only shows numbers as fractions if the fractions are exact rather than approximating fractions?

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## HP Prime showing square roots as fractions

03-27-2019 06:26 AM

Is your Prime displaying those fractions immediately after performing the calculation, or are you pressing something else (for example the [a b/c] key) next? Please tell us exactly what you press before seeing these results. Otherwise we can't duplicate what you're seeing.

Are you seeing these fractions in Home view or in CAS view?

What is your current display mode (Standard? Fixed? Number of digits...)?

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## HP Prime showing square roots as fractions

03-27-2019 10:38 AM - edited 03-27-2019 10:41 AM

Sorry for not specifying. This is after I click a b/c. I tried it in both CAS and Home, and it shows the fractions. I do not want it to show fractions unless they are exact. I am in standard mode.

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## HP Prime showing square roots as fractions

03-27-2019 01:56 PM - edited 03-27-2019 02:00 PM

The __first__ press of [a b/c] __in Home view__ displays the result of QPI(x), which is usually what you're looking for. See the built-in Help screen about QPI for more information about it. (EDIT: If your Prime doesn't have the QPI function in its command set, then you are using an obsolete version of the firmware. Connect to the HP Connectivity Kit software ASAP and upgrade your Prime.)

However, the second press of [a b/c] in Home view displays the simplest fraction which is close to x. You can control the accuracy by setting different display modes. For example, PI is displayed as 312689/99532 in Standard mode, but as 201/64 in Fixed 3 mode.

If x>1, then the third press of [a b/c] in Home view rewrites the previous fraction as a mixed number.

Pressing [a b/c] __in CAS view__ always returns a fraction for x, but its accuracy is controlled by the current value of Epsilon (on the second page of the CAS Settings screen), not by the display setting.

Please note that the purpose of the [a b/c] key is to return user-adjustable approximations in fraction form. In other words, if you want to find a fraction that's as simple as possible (smallest numerator and denominator) within a given range of x, then that's what [a b/c] does. If you only want the original non-fractional form, press it only once in Home mode and you MIGHT get what you want, if Prime can figure it out. Subsequent presses in Home, or any press in CAS, will always return a fraction. No, there is no way to disable that behavior, because acting that way is its stated purpose.

Disclaimer: I don't work for HP, but I created the algorithm that [a b/c] uses in Home view to generate its fraction outputs.

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## HP Prime showing square roots as fractions

03-27-2019 02:21 PM

Thanks. I have 2 more questions. I tried getting the calculator to simplify the indefinite integral of 2xcos(x^2) but it isn’t working. Is this too complex or something? Also, I was wondering how to graph integrals because it does not work and just shows NaN in the table when I try in the Function app.