人教版八年级数学上册第十五章 分式 专题练习题
专题(一) 分式的运算与化简求值
1.计算:
(1)2a a +1-2a -4a 2-1÷a -2a 2-2a +1
; 解:原式=2a a +1-2(a -2)(a -1)(a +1)·(a -1)2a -2
=2a a +1-2(a -1)a +1
=
2a +1.
(2)(1-1a -1)÷a 2
-4a +4a 2-a
; 解:原式=(a -1a -1-1a -1)÷(a -2)2a (a -1)
=a -2a -1·a (a -1)(a -2)2 =a a -2.
(3)(a +9-4a a -2)÷a 2-9a -2
; 解:原式=a (a -2)+(9-4a )a -2·a -2(a +3)(a -3)
=a 2-2a +9-4a (a +3)(a -3)
=(a -3)2(a +3)(a -3)