知识点比较 12a 22 23 22 23 22 +b 22 2 32 +b2 2 12 13 12 13 12 12 13 2 23 21 23 2a21a2+b22 23 +b 32 31 32 32 203312 12 2 11 13 21 2 23 31 3 2 2 3 3 2 3 2 a b a b a a a a a a b a + + + = 11 13 11 13 21 23 21 23 31 33 12 12 22 22 32 31 3 32 3 a a a a a a a a a a b a b a b a a a + 知识点比较 11 13 11 13 11 13 21 23 21 23 21 23 31 33 31 3 12 12 12 12 22 22 22 22 32 32 32 3 31 33 32 a a a a a a b a b a b a b a b a b a a a a a a a a a a a a a + + +             +                    11 13 11 13 11 13 21 23 21 23 21 23 31 33 31 33 12 12 12 12 22 22 22 22 32 32 32 32 31 33 2 2 2 2 2 2 a a b a b a b a a a a a a a a a a a a a a a a a a b a b a b             + =                 +  +  +