(1) | - 3 | - ( 5 + 1 ) 0 + ( - 2 ) 2 ;
(2) ( 1 - 3 a ) ÷ a - 3 a 2 .
化简:.
计算:.
计算①–2-5+23-9+7 ② ③ ④
(本题6分)计算:
计算: (1) (2)