Solving with the built-in equations of the 35s - Printable Version +- HP Forums (https://archived.hpcalc.org/museumforum) +-- Forum: HP Museum Forums (https://archived.hpcalc.org/museumforum/forum-1.html) +--- Forum: Old HP Forum Archives (https://archived.hpcalc.org/museumforum/forum-2.html) +--- Thread: Solving with the built-in equations of the 35s (/thread-232896.html) Solving with the built-in equations of the 35s - Palmer O. Hanson, Jr. - 10-15-2012 Page 7-6 of the 35s manual describes use of the built-in equations from the keyboard. I would like to use the "2x2 lin solve" equation in a program. How do I do that? Re: Solving with the built-in equations of the 35s - Gene Wright - 10-16-2012 This should show how. Good to finally meet you a few weeks ago in Nashville! Re: Solving with the built-in equations of the 35s - Andrew Feist - 10-16-2012 I don't think you do--I think you can only type your own equations into a program, not use the ones that are built in. Re: Solving with the built-in equations of the 35s - Gene Wright - 10-16-2012 Ah, I mis-read your original question. You cannot use one of the built-in equations in a user program. Sorry! Re: Solving with the built-in equations of the 35s - Dieter - 10-17-2012 You cannot use equations from the 35s equation list in your own programs. But solving a 2x2 system is so trivial that it can be done in a very short user routine: ```RCL A RCL* F RCL D RCL* C - RCL A RCL* E RCL B RCL* D - / ENTER RCL* B +/- RCL+ C RCL/ A ``` This returns the two unknowns in X and Y. Actually you can also do this in just two lines, using the EQN-feature: ```([A,D]*[F,-C])/([A,B]*[E,-D]>G) ([C,B]*[E,-F])/G ``` Type "STO G" to enter ">G". Please also note that the minuses are unary (signs, not operators). This solution also works for A=0. ;-) Dieter Edited: 17 Oct 2012, 3:28 p.m.