Bài 13

a1 = float(input("He so a cua BPT 1 (a1*x + b1 > 0): "))
b1 = float(input("He so b cua BPT 1: "))
a2 = float(input("He so a cua BPT 2 (a2*x + b2 <= 0): "))
b2 = float(input("He so b cua BPT 2: "))

# BPT 1: a1*x + b1 > 0
if a1 > 0:
    x_min = -b1 / a1
    print(f"BPT 1: x > {x_min}")
    bien_trai = x_min
    mo_trai = True     # kieu ho (khong bao gom)
elif a1 < 0:
    x_max_1 = -b1 / a1
    print(f"BPT 1: x < {x_max_1}")
    bien_trai = None
else:
    bien_trai = None

# BPT 2: a2*x + b2 <= 0
if a2 > 0:
    x_max = -b2 / a2
    print(f"BPT 2: x <= {x_max}")
elif a2 < 0:
    x_min_2 = -b2 / a2
    print(f"BPT 2: x >= {x_min_2}")

# Thong bao giao
if a1 > 0 and a2 > 0:
    trai = -b1/a1
    phai = -b2/a2
    if trai < phai:
        print(f"Giao: ({trai}; {phai}]")
    else:
        print("Giao: Rong (khong co nghiem chung)")