Not simplifying?

[DaftHuman01]

Hi, Im trying to use the simplify function in the CAS of my HP Prime. But when I try to simplify the equation, it just gives the same thing back. I attached the equation and what its result should be. Does anyone know what I can do or what settings I need to apply for this to work properly? Thanks!

[KeithB]

Can you show us what you tried on the prime?

[CheshireChris]

(09-24-2024 03:12 PM)KeithB Wrote:  Can you show us what you tried on the prime?

I've tried it myself, Keith. If you go to the CAS module of the Prime and enter this equation (with the multiplication signs included, of course) and tap the "Simplify" soft button, you get back what you entered.

[Patocuy]

Hi

CAS works better with exact quantities. I assumed that V1 and V2 are variables (no multiplication sign needed) and coefficients for variable j are -5/2, 2 and 4. The results are not what the OP expected anyway but one of them shows that j could be eliminated easily (regroup function).

[KeithB]

" j are -5/2, 2 and 4."
He is obviously an electrical engineer. j is i, the sqrt(-1).

[DaftHuman01]

(09-24-2024 03:12 PM)KeithB Wrote:  Can you show us what you tried on the prime?

Yes, I attached it. However, I was able to figure it out as can also be seen in the attachment. A bit of algebra still has to be done to get the desired form of the answer but its good enough, unless you do know of a way to get it into that form.

[KeithB]

Change "2.5" to 25/10.

[C.Ret]

(10-01-2024 03:37 PM)KeithB Wrote:  Change "2.5" to 25/10

Bonjour,

This is the trick that simplifies the manipulations in the HP Prime CAS. This trick has saved my day many times. Everything is easier with exact coefficients.
It is not only useful in solvers but also on the command line.

But, we may also do without it, but it requires a little more attention and more instructions.

The following screenshot shows two paths to go from the equation \( \frac{2v_1}{-2.5j}+\frac{v_1-v_2}{4j}=\frac{v_2}{2j} \) to the linear equation \( 11\cdot v_1 + 15\cdot v_2=0 \). Obviously, there are many others paths, including those many that I took by trial and error before using the trick given by KeithB that makes thinks so easy.

[parisse]

I would suggest something like:
j:=i;
exact(original_input)

[C.Ret]

Yes, thank you, parisse.

Two excellent suggestions!

The assignment allows the use of the exact original formula, and the exact command helps avoid any errors when converting coefficients and rearranging them into a more conventional format, ensuring no imaginary values are left in the numerators.



Much simpler! The exact command makes everything so straightforward and reliable. Even though I had forgotten about this powerful command, I really appreciate how the CAS simplifies algebraic transformations, making them more convenient, clearer, and, most importantly, error-free. I tend to make silly mistakes—forgetting something or misplacing a sign, which can ruin the entire process.

Using the HP Prime in CAS mode enables secure, step-by-step algebraic operations.

What an impressive and powerful tool the HP Prime is. Thanks again!