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> ①已知菱形的一条对角线为6cm,面积为183cm2,求这个菱形的边长.②先化简,再求值.x2-2xx2-1÷(x-1-2x-1x+1),其中x=12.-数学
①已知菱形的一条对角线为6cm,面积为183cm2,求这个菱形的边长.②先化简,再求值.x2-2xx2-1÷(x-1-2x-1x+1),其中x=12.-数学
题目简介
①已知菱形的一条对角线为6cm,面积为183cm2,求这个菱形的边长.②先化简,再求值.x2-2xx2-1÷(x-1-2x-1x+1),其中x=12.-数学
题目详情
①已知菱形的一条对角线为6cm,面积为
18
3
c
m
2
,求这个菱形的边长.
②先化简,再求值.
x
2
-2x
x
2
-1
÷(x-1-
2x-1
x+1
)
,其中
x=
1
2
.
题型:解答题
难度:中档
来源:不详
答案
①设菱形的另一对角线长为x,
根据题意得,
class="stub"1
2
×6•x=18
3
,
解得x=6
3
,
所以,两对角线的一半分别为3cm,3
3
cm,
边长=
3
2
+(3
3
)
2
=6cm;
②
x
2
-2x
x
2
-1
÷(x-1-
class="stub"2x-1
x+1
),
=
x(x-2)
(x+1)(x-1)
÷
x
2
-2x
x+1
,
=
x(x-2)
(x+1)(x-1)
•
class="stub"x+1
x(x-2)
,
=
class="stub"x
x-1
,
当x=
class="stub"1
2
时,原式=
class="stub"1
2
class="stub"1
2
-1
=-1.
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题目简介
①已知菱形的一条对角线为6cm,面积为183cm2,求这个菱形的边长.②先化简,再求值.x2-2xx2-1÷(x-1-2x-1x+1),其中x=12.-数学
题目详情
②先化简,再求值.
答案
根据题意得,
解得x=6
所以,两对角线的一半分别为3cm,3
边长=
②
=
=
=
当x=