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化简: ( 2 m m 2 − 4 + 1 2 − m ) ÷ 1 m + 2 = .
下列计算正确的是 ( )
3 a 2 + 4 a 2 = 7 a 4
a 2 ⋅ 1 a = 1
− 18 + 12 ÷ ( − 3 2 ) = 4
a 2 a − 1 − a − 1 = 1 a − 1
(1)计算: 3 - 1 - 1 9 + ( 3 - 3 ) 0 ;
(2)化简: ( 1 - 1 x ) ÷ 2 x - 2 x 2 .
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