通分并比较大小.78和56912和1318320、58和45.-数学

题目简介

通分并比较大小.78和56912和1318320、58和45.-数学

题目详情

通分并比较大小.
7
8
5
6

9
12
13
18

3
20
5
8
4
5
题型:解答题难度:中档来源:不详

答案

(1)class="stub"7
8
class="stub"5
6

class="stub"7
8
=class="stub"7×3
8×3
=class="stub"21
24

class="stub"5
6
=class="stub"5×4
6×4
=class="stub"20
24

因为class="stub"21
24
>class="stub"20
24
,所以class="stub"7
8
>class="stub"5
6


(2)class="stub"9
12
class="stub"13
18

class="stub"9
12
=class="stub"9×3
12×3
=class="stub"27
36

class="stub"13
18
=class="stub"13×2
18×2
=class="stub"26
36

因为class="stub"27
36
>class="stub"26
36
,所以class="stub"9
12
>class="stub"13
18


(3)class="stub"3
20
class="stub"5
8
、和class="stub"4
5

class="stub"3
20
=class="stub"3×2
20×2
=class="stub"6
40

class="stub"5
8
=class="stub"5×5
8×5
=class="stub"25
40

class="stub"4
5
=class="stub"4×8
5×8
=class="stub"32
40

因为class="stub"6
40
<class="stub"25
40
<class="stub"32
40
,所以class="stub"3
20
<class="stub"5
8
<class="stub"4
5

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