Solve for x using python

Question

I came across a problem. One string is taken as input say

input_string = "12345 + x = x * 5 + (1+x)* x + (1+18/100)"

And get output of x using python. I am not able to figure out logic for this.

Answer 1

Here is a complete SymPy example for your input:

from sympy import Symbol, solve, Eq
from sympy.parsing.sympy_parser import parse_expr

input_string = "12345 + x = x * 5 + (1+x)* x + (1+18/100)"
x = Symbol('x', real=True)
lhs = parse_expr(input_string.split('=')[0], local_dict={'x':x})
rhs = parse_expr(input_string.split('=')[1], local_dict={'x':x})

print(lhs, "=", rhs)
sol = solve(Eq(lhs, rhs), x)
print(sol)
print([s.evalf() for s in sol])

This outputs:

x + 12345 = x*(x + 1) + 5*x + 59/50
[-5/2 + 9*sqrt(15247)/10, -9*sqrt(15247)/10 - 5/2]
[108.630868798908, -113.630868798908]

Note that solve() gives a list of solutions. And that SymPy normally does not evaluate fractions and square roots, as it prefers solutions without loss of precision. evalf() evaluates a float value for these expressions.