Factorial equation

[Quadratica]

Playing about with the Prime

(n+2)! = 4*n! +4*(n+1)!

Simple to solve by hand

My attempts at getting the Prime to solve it fail.

TI nSpire CAS solves it correctly

Geo-Gebra fails

Any help is welcome.

[calc_freak]

I just copied your equation and pasted it into the Solve app on my Prime emulator. Click the Num key and then the Solve soft key. It spit out 3 as the answer. Same result on my iOS version.

[C.Ret]

Hi, you are welcome.

That's right, directly typing SOLVE((n+2)!=4n!+4(n+1)!,n) results in an error message (see first line in the following screenshot).

(10-20-2023 08:39 PM)Quadratica Wrote:  Simple to solve by hand

This is the detail of great importance that lead you to one the turnaround (see second line in screenshot).

But, there is a lot of other way to get the answer without any effort (see last entry in the screenshot).

   

I hope this help a bit.

[Quadratica]

Both suggestions work. It's annoying that it requires a little workaround which would not be the case on other types of equations. I didn't know that the option to specify a range for the solution existed and it's good to know.

Thank you