find_roots.py

import math


def find_roots(a, b, c):
    if a == 0:
        return print('Erreur: a est égal à 0.')

    delta = b ** 2 - 4 * a * c

    print()
    print("Δ =", delta)
    print()

    if delta < 0:
        return print('Pas de solutions possibles, delta est plus petit que zéro')

    if delta > 0:
        print("x1 = -b - sqrt(Δ) / 2a")
        print("   = {} - sqrt({}) / 2 * {}".format(-b, delta, a))
        print("   = {} - {} / {}".format(-b, math.sqrt(delta), 2 * a))
        print("   = {} / {}".format(-b - math.sqrt(delta), 2 * a))
        print('   = {}'.format((-b - math.sqrt(delta)) / (2 * a)))
        print("\n")
        print("x2 = -b + sqrt(Δ) / 2a")
        print("   = {} + sqrt({}) / 2 * {}".format(-b, delta, a))
        print("   = {} + {} / {}".format(-b, math.sqrt(delta), 2 * a))
        print("   = {} / {}".format(-b - math.sqrt(delta), 2 * a))
        print('   = {}'.format((-b + math.sqrt(delta)) / (2 * a)))

    if delta == 0:
        print('x1 = -b / 2a')
        print('x1 = {} / {}'.format(-b, 2 * a))
        print('x1 = {}'.format(-b / (2 * a)))

a = input('a: ')
b = input('b: ')
c = input('c: ')

find_roots(int(a), int(b), int(c))

output.txt

a: 2
b: -1
c: -6

f(x) = ax²+bx+c
f(x) = 2x²+-1x+c

Δ = 49

x1 = -b - sqrt(Δ) / 2a
   = --1 - sqrt(49) / 2 * 2
   = --1 - 7.0 / 4
   = -6.0 / 4
   = -1.5


x2 = -b + sqrt(Δ) / 2a
   = --1 + sqrt(49) / 2 * 2
   = --1 + 7.0 / 4
   = -6.0 / 4
   = 2.0

variation.py

def variation(vd, va):
    return ((va - vd) / vd) * 100


va = input('va: ')
vd = input('vd: ')

print('variation = (va - vd / vd) * 100')
print(variation(int(vd), int(va)))