Need help with this problem:(

[CharlieAlfa]

Hi...
When i try to use solve() to solve a 2 var ecc. its send me a error messagge:
The ecuation is:
solve((0.6=y*q^2)/(176.4*y),y)
and the message is:
["Not implemented, e.g. for multivariate mod/approx polynomials Error: Bad Argument Type"]
Please i need to fix it before tomorrow cause i have an exam T.T
Thanks

[Tonig00]

O.6/(176.4 * y) = q^2 / 176.4

y = 0.6 / q^2


In cas, if I understood the problem the prime g2 gives the solution.
Maybe you have to "collect()" the result

[roadrunner]

You need to make it into an exact equation like this:

solve((6/10) = (y+(q^2/(1764*y/10))),y)

the answers are:

{((-sqrt(-250*q^2+3969)+63)/210),((sqrt(-250*q^2+3969)+63)/210)}

For some reason the CAS couldn't or wouldn't solve it as you wrote it.

-road

[chromos]

[Lukas]

Interesting find... it seems to be a general problem with giac though, not just HP Prime's implementation.

Or at least solve(.6 = y+(q^2)/(176.4*y),y) just kills giac 1.9.0 on my computer ("Segmentation fault (core dumped)"), whereas it can handle solve((6/10) = (y+(q^2/(1764*y/10))),y) just fine.

[cdmackay]

Perhaps it's related to CAS storing numbers in binary format, which can't represent all decimals exactly?

[Albert Chan]

I think solve with approximate number switched to fsolve.
But q is still symbolic, thus fsolve unable to handle.