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> (1)先化简、再求值:12x-1x+y(x2-y2+x+y2x),其中x=2,y=3.(2)先化简、再求值:a-32a-4÷(5a-2-a-2),其中a=3-3.-数学
(1)先化简、再求值:12x-1x+y(x2-y2+x+y2x),其中x=2,y=3.(2)先化简、再求值:a-32a-4÷(5a-2-a-2),其中a=3-3.-数学
题目简介
(1)先化简、再求值:12x-1x+y(x2-y2+x+y2x),其中x=2,y=3.(2)先化简、再求值:a-32a-4÷(5a-2-a-2),其中a=3-3.-数学
题目详情
(1)先化简、再求值:
1
2x
-
1
x+y
(
x
2
-
y
2
+
x+y
2x
)
,其中x=
2
,y=3.
(2)先化简、再求值:
a-3
2a-4
÷(
5
a-2
-a-2)
,其中a=
3
-3
.
题型:解答题
难度:中档
来源:不详
答案
(1)原式=
class="stub"1
2x
-
class="stub"1
x+y
(x+y)(x-y)-
class="stub"1
x+y
•
class="stub"x+y
2x
=
class="stub"1
2x
-(x-y)-
class="stub"1
2x
=-(x-y)
=y-x,
当x=
2
,y=3时,
原式=3
-
2
;
(2)原式=
class="stub"a-3
2(a-2)
÷[
5-(a+2)(a-2)
(a-2)
]
=
class="stub"a-3
2(a-2)
•
class="stub"a-2
9-
a
2
=
class="stub"a-3
2(a-2)
•
class="stub"a-2
(3+a)(3-a)
=
-
class="stub"1
2(a+3)
,
当a=
3
-3时,原式=-
class="stub"1
2(
3
-3+3)
=-
3
6
.
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题目简介
(1)先化简、再求值:12x-1x+y(x2-y2+x+y2x),其中x=2,y=3.(2)先化简、再求值:a-32a-4÷(5a-2-a-2),其中a=3-3.-数学
题目详情
(2)先化简、再求值:
答案
=
=-(x-y)
=y-x,
当x=
原式=3-
(2)原式=
=
=
=-
当a=