先化简,再求值: a + 3 a ⋅ 6 a 2 + 6 a + 9 + 2 a - 6 a 2 - 9 ,其中 a = 3 - 1 .
计算:
计算: (1) (2)
计算: (1)(+45)+(-92)+5+(-8) (2) (3)÷ (4)+︱6-10︱-