HP Prime not able to solve system of equations

[danvail]

I'm running an HP Prime on the newest firmware version, and went to solve the following system of equations in the solve app:

1.) X=3*Y-9

2.) X*Y=5670

After inputting the values and going to the solve numeric view, pressing Solve results in a message saying "Cannot find solution". I've verified that this solution is solvable with the solution (Y=45, X=126). Can anyone explain why the Prime can't solve this, or if I'm doing something wrong?

[Maké]

Hi!, @Danvail :

See the images and compare with Wolfram Alpha ...

In CAS MODE, select Exact.

[danvail]

Thank you! I was trying to use the solve app which was causing the problem, but using that command in the CAS environment works great, and is probably faster.

[Tim_Wessman]

The reason why the solving is not working for you is because it is using a "numerical" method in the solve app. Numerical methods you can think of as a very fast, "guess and check" that will converge to a number that is "close enough". If your initial guesses are too far off - especially in misbehaved or very large changing functions - they do not converge unless close. Your functions are very steep and do not behave nicely in this instance with your initial guesses.

Put some intial guesses in the solve app closer to your result, and it WILL jump to them like you expect.