def kaifa(x, n, error):
    x0 = x
    err = 1
    x = x0/n
    if x0 == 1:
        x = 1
    elif x == 0:
        x == 0
    elif x < 0:
        print('输入参数错误！')
        return 0
    else:
        while err > 10**(-1*error):
            x = x - (x**n-x0)/(n*x**(n-1))
            err = abs(x**n-x0)
    print('{}的1/{}次方是{:.7f}'.format(x0, n, x))


for i in range(-1, 9):
    kaifa(i, 2, 7)
    kaifa(i, 3, 7)