Re: What is causing this error message?

*To*: mathgroup at smc.vnet.net*Subject*: [mg57575] Re: [mg57537] What is causing this error message?*From*: Murray Eisenberg <murray at math.umass.edu>*Date*: Wed, 1 Jun 2005 06:02:47 -0400 (EDT)*Organization*: Mathematics & Statistics, Univ. of Mass./Amherst*References*: <200505310900.FAA03456@smc.vnet.net>*Reply-to*: murray at math.umass.edu*Sender*: owner-wri-mathgroup at wolfram.com

You have (at least) two errors in the input cell you show: (1) Presumably you want the terms x y and x y^2 rather than xy and xy^2. (The latter pair would refer to a two-letter variable "xy".) (2) You need the double-equal sign == to indicate an equation. (By contrast, the single-equals = is used to assign values, which is shorhand for the Set function.) Such examples are a good way to learn how Mathematica works, but it's also a very good idea to do start at the beginning of the part "A Practical Introduction to Mathematica" to learn such basic syntactical notions as well as the semantics of them. Bookreader wrote: > NSolve[{x^3y + xy - 10 = 0, xy^2 - xy + 6 = 0}, {x, y}] > > Set::write: Tag Plus in -10 + x y + x^3 y is Protected. More? > > Please tell me how to correct this. -- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305