You can define equations in Python using SymPy and symbolic math variables. Equations in SymPy are different than expressions. An expression does not have equality. An expression is a collection of symbols and operators, but expressions are not equal to anything. Equations have equality. An equation can be thought of as an expression equal to something else.
A code section that defines the equation 4x + 2 = 0 is below. Note all equations defined in SymPy are assumed to equal zero.
from sympy import symbols, Eq
x = symbols('x')
eq1 = Eq(4*x + 2)
x, y = symbols('x y') eq2 = Eq(2*y - x - 5)
Alternatively, an equation can be defined with a left hand side and a right hand side passed as separate arguments.
x, y = symbols('x y')
eq2 = Eq(2*y - x, 5)
Substitutions in Equations
Symbols and expressions can be substituted into equations. In the code section below, the variable z is substituted in for the variable x (z replaces x).
x, y, z = symbols('x y z')
eq2 = Eq(2*y - x - 5) eq3 = eq2.subs(x,z) eq3
Eq(2*y - z - 5, 0)