计算: 18 - ( π - 5 ) 0 + | 2 2 - 3 | .
化简: ( x - 5 + 16 x + 3 ) ÷ x - 1 x 2 - 9 .
计算: 12 - | 1 - 3 | + ( 7 + π ) 0 .
化简: ( a 2 + 7 a - 3 a 2 - 9 - a + 4 a + 3 ) ÷ a + 3 a - 3 .
计算: ( - 3 ) 2 + | 2 - 5 | - 20 .