Add exercises 1, 2 and 3

Activity_3_python/exercise_2/ex2_5.py

@@ -0,0 +1,20 @@
+from math import*
+
+print("Résolution de l'équation du second degré : ax² + bx + c = 0")
+a = float(input("Coefficient a ?"))
+b = float(input("Coefficient b ?"))
+c = float(input("Coefficient c ?"))
+
+discriminant = (b**2)/(4*a*c)
+
+print("Discriminant : ",discriminant)
+
+if discriminant > 0:
+    print("Deux solutions :")
+    print((-b-sqrt(discriminant))/(2*a))
+    print((-b+sqrt(discriminant))/(2*a))
+elif discriminant == 0:
+    print("Une solution :")
+    print(-b/(2*a))
+else:
+    print("Pas de solution !")