Title: Linear equations solver in 3 lines
Submitter: Maxim Krikun (other recipes)
Last Updated: 2005/01/31
Version no: 1.1
Category: Programs

Description:

Just a little bit of hack: a linear equations solver using eval and built-in complex numbers:
>>> solve("x - 2*x + 5*x - 46*(235-24) = x + 2")
3236.0

Source: Text Source

def solve(eq,var='x'):
    eq1 = eq.replace("=","-(")+")"
    c = eval(eq1,{var:1j})
    return -c.real/c.imag

Discussion:

One could add one more line to insert '*' where needed, i.e. "100x" -> "100*x",
add some input validation, in particular check whether the equation is actually linear and not quadratic or cubic, and finally add a GUI to solve and plot multiple linear functions using different colors and get a nice tool for use in elementary mathematical education.

See also "Manipulate simple polynomials in Python" by Rick Muller
http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/362193