Python基础学习：求一元二次方程的解

# 定义一个函数quadratic(a, b, c)，接收3个参数，返回一元二次方程
# ax ^ 2 + bx + c = 0
# 计算平方根可以调用math.sqrt()函数
import math
# print(help(math.sqrt))


def quadratic(a, b, c):
    s = (b ** 2) - (4 * a * c)
    if a == 0:
        if b == 0:
            return '此方程无解'
        else:
            x = -c / b
            if abs(x) % 1 == 0:
                return '此方程为一元一次方程，解x=%d' % x
            else:
                return '此方程为一元一次方程，解x=%.2f' % x
    elif s < 0:
        return '此方程无解'
    else:
        sq = math.sqrt(s)
        x1 = (-b + sq)/(2*a)
        x2 = (-b -sq)/(2*a)
        if x1 == x2:
            if abs(x1) % 1 == 0:
                return 'x1=x2=%d' % x1
            else:
                return 'x1=x2=%.2f' % x1
        elif abs(x1) % 1 == 0 and abs(x2) % 1 == 0:
            return 'x1=%d,x2=%d' % (x1, x2)
        else:
            return 'x1=%.2f,x2=%.2f' % (x1, x2)

print(quadratic(1,2,1))