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 (1). (2).
计算: (1) (2).
(1)计算:2sin60°+|-3|--()-1 (2)化简:3(x2+2)-3(x+1)(x-1)
(1)计算:; (2)解方程:.
计算: (1)(+-2.75)×(-24); (2)-32+(-2-5)÷7+|-|×(-2)2.