给定a=8 b=3根据如下公式计算x1并保留两位小数； $$ x = sqrt a + b a - b a^2 + b^2 $$# Q2：将x1代入下列分段函数计算结果赋值给x2 Q3：计算x1100所对应的成绩等级赋值给y 90分以上含90分输出A；80分-90分不含90分输出B；70分-80分不含80分输出C；60分-70分不含70分输出D；60分以下输出E。python 代码

import math

a = 8
b = 3

x1 = round(math.sqrt((a + b) * (a - b) / (a**2 + b**2)), 2)

if x1 >= 90:
    x2 = 4
elif x1 >= 80:
    x2 = 3
elif x1 >= 70:
    x2 = 2
elif x1 >= 60:
    x2 = 1
else:
    x2 = 0

y = x1 * 100

if y >= 90:
    grade = 'A'
elif y >= 80:
    grade = 'B'
elif y >= 70:
    grade = 'C'
elif y >= 60:
    grade = 'D'
else:
    grade = 'E'

print("x1 =", x1)
print("x2 =", x2)
print("y =", y)
print("Grade =", grade)