import math
def quadratic(a,b,c):
	x1=(math.sqrt(b*b-4*a*c)-b)/2/a
	x2=(-math.sqrt(b*b-4*a*c)-b)/2/a
	return x1,x2

print('quadratic(2, 3, 1) =', quadratic(2, 3, 1))
print('quadratic(1, 3, -4) =', quadratic(1, 3, -4))

if quadratic(2, 3, 1) != (-0.5, -1.0):
    print('测试失败')
elif quadratic(1, 3, -4) != (1.0, -4.0):
    print('测试失败')
else:
    print('测试成功')