问题
解答题
解答下列各题: (1)计算:(1-2
(2)先化简,再求值:
|
答案
(1)原式=1-
-3+1 4
=-1 2
;7 4
(2)原式=
-a2+a-3 a-2
•(a+1)2 a-2 1 a+1
=a2+a-3-a-1 a-2
=
=a+2,(a+2)(a-2) a-2
当a=
+2时,原式=2
+4.2
解答下列各题: (1)计算:(1-2
(2)先化简,再求值:
|
(1)原式=1-
-3+1 4
=-1 2
;7 4
(2)原式=
-a2+a-3 a-2
•(a+1)2 a-2 1 a+1
=a2+a-3-a-1 a-2
=
=a+2,(a+2)(a-2) a-2
当a=
+2时,原式=2
+4.2