试题与答案

用递等式计算.(怎样简算怎样算)(1)54×52+54×32(2)13÷5+23

题型:解答题

题目:

用递等式计算.(怎样简算怎样算)
(1)
5
4
×
5
2
+
5
4
×
3
2

(2)
1
3
÷5+
2
3
×
1
5

(3)(
4
7
+
1
2
)×28
(4)[1-(
3
7
+
5
14
)]÷
1
7

答案:

(1)

5
4
×
5
2
+
5
4
×
3
2

=(

5
2
+
3
2
)×
5
4

=4×

5
4

=5;

(2)

1
3
÷5+
2
3
×
1
5

=

1
3
×
1
5
+
2
3
×
1
5

=(

1
3
+
2
3
)×
1
5

=1×

1
5

=

1
5

(3)(

4
7
+
1
2
)×28,

=

4
7
×28+
1
2
×28,

=16+14,

=30;

(4)[1-(

3
7
+
5
14
)]÷
1
7

=[1-

11
14
]×7,

=

3
14
×7,

=1

1
2

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