[Python] 使用 sympy 解聯立方程組

4x + 3y + 3z = 350

4x + 2y + 5z = 360

8x + 8y + 10z = 840

from sympy import *

x = Symbol('x')
y = Symbol('y')
z = Symbol('z')

f1 = 4*x + 3*y + 3*z - 350
f2 = 4*x + 2*y + 5*z - 360
f3 = 8*x + 8*y + 10*z - 840

sol = solve((f1, f2, f3), x, y, z)
pprint(sol)
# OUT: {x: 50, y: 30, z: 20}

使用 evalf 將分數轉為小數輸出

ex.

4x² + 5x - 6 = 0

from sympy import *
x = Symbol('x')
f = 4*x**2 + 5*x -6
sol = solve(f, x)
pprint(sol)
# OUT: [-2, 3/4]
print sol[1].evalf()
# OUT: 0.750000000000000