L. B.

如果你想让它更具可读性,这是另一种选择:

def beauty(coeff, i):

    if(coeff == 0): return ''

    if(i == 2):

        if(coeff ==  1): return  "x\u00B2"
        if(coeff == -1): return "-x\u00B2"
        return f"{coeff}x\u00B2"

    if(i == 1):

        if(coeff ==  1): return "+x"
        if(coeff == -1): return "-x"
        if(coeff  >  0): return f"+{coeff}x"
        return f"{coeff}x"

    if(i == 0):

        if(coeff >  0): return f"+{coeff}"
        return f"{coeff}"


def PrintQuadratic():

    a = int(input('a: '))
    b = int(input('b: '))
    c = int(input('c: '))

    print(f"{beauty(a,2)}{beauty(b,1)}{beauty(c,0)}")

PrintQuadratic()
a: 7
b: 9
c: 13
→ 7x²+9x+13

PrintQuadratic()
a: -1
b:  1
c:  0
→ -x²+x

PrintQuadratic()
a: 4
b: -2
c: 1
→ 4x²-2x+1

它有点长,但能产生很好的指纹。