先化简,再求值: ( x 2 - y x - x - 1 ) ÷ x 2 - y 2 x 2 - 2 xy + y 2 ,其中 x = 2 , y = 6 .
计算: - 2 × - 27 3 + | 1 - 3 | - ( 1 2 ) - 2
解方程: 5 x - 8 x 2 - 9 - 1 = 3 - x x + 3 .
计算: - 2 × ( 3 ) 2 + | 5 - 3 | - ( - 65 ) 0 .
化简: ( a + 1 a - 1 - a a + 1 ) ÷ 3 a + 1 a 2 + a .
计算: ( - 3 ) × ( - 6 ) + | 2 - 1 | + ( 5 - 2 π ) 0