HP35S - Cubic (and incidentally quadratic) equations solver

[Roberto Volpi]

(04-07-2023 07:55 PM)PedroLeiva Wrote:  Nice program Roberto, thanks for sharing. Just to see if I understood the instructions and didn't make typing mistakes, ¿could you give me two numerical examples, one for cubic and the other for quadratic?. Pedro

Thanks Pedro

Let's take as example the following quadratic EQN:

x^2 -x -12

Here how to calculate both roots:

Press 1
Press ENTER
Press -1
Press ENTER
Press -12
Press XEQ E ENTER

The calculator will give following result:

Stack Y: -3 i 0 (1st root)
Stack X: 4 i 0 (2nd root)

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Now a quick example of cubic EQN:

x^3 -13x -12

Here how to calculate all 3 roots:

Press 1
Press ENTER
Press 0
Press ENTER
Press -13
Press -12
Press XEQ C ENTER

The calculator will give as result:

Stack Y: 0.000001 (theoretical approximation)
Stack X: 4 (1st root, always real)

Press R/S

The calculator will give as result:

Stack Y: -3 i 0 (2nd root)
Stack X: -1 i 0 (3rd root)

in case you forget to take note of 1st root, just press RCL G.