Error while trying to use Sympy for the Law of Supply and Demand in Python

Question

I am trying to solve an exercise about the Law of Supply and Demand

I have the following equations:

Supply: S(q):(q**2) + β + 10

Demand: D(q):(q - 20)**2

I want to solve it with β values to be from 0 to 10.

I made the following code

import sympy as sy

def S(q, β):
    return (q**2) + β + 10

def D(q):
    return (q - 20)**2

for i in range(11):
    β = i
    q = sy.Symbol('q')
    eq = sy.Eq(S(q,β), D(q))
    q_sol = sy.solve(eq)
    p_sol = S(q_sol[0], β)
    print(q_sol, p_sol)

But I get the following results instead of a float:

[39/4] 1681/16

[389/40] 168921/1600

[97/10] 10609/100

[387/40] 170569/1600

[193/20] 42849/400

[77/8] 6889/64

[48/5] 2704/25

[383/40] 173889/1600

[191/20] 43681/400

[381/40] 175561/1600

[19/2] 441/4

Answer 1

You are seeing the exact Rational numbers that SymPy can work with. To convert them to Float, use the n or evalf method:

>>> from sympy import Rational
>>> Rational(22, 7)
22/7
>>> _.n()
3.14285714285714