题目内容
(2012?北京)用合理的方法计算.
(1)8(x-2)=2(x+7)
(2)
×2012
(3)(
+
)×8+
(4)
×(
+
+
)
(5)
×[1÷(
-
)].
(1)8(x-2)=2(x+7)
(2)
| 2010 |
| 2011 |
(3)(
| 5 |
| 8 |
| 1 |
| 27 |
| 19 |
| 27 |
(4)
| 3 |
| 5 |
| 1 |
| 7 |
| 8 |
| 21 |
| 2 |
| 3 |
(5)
| 1 |
| 6 |
| 3 |
| 5 |
| 3 |
| 10 |
分析:(1)根据等式的性质进行解答;
(2)2012=2011+1,然后再根据乘法分配律进行简算;
(3)根据乘法分配律进行简算;
(4)先算小括号里面的加法,再算乘法;
(5)先算减法,再算除法,最后算乘法.
(2)2012=2011+1,然后再根据乘法分配律进行简算;
(3)根据乘法分配律进行简算;
(4)先算小括号里面的加法,再算乘法;
(5)先算减法,再算除法,最后算乘法.
解答:解:(1)8(x-2)=2(x+7),
8x-16=2x+14,
8x-16-2x=2x+14-2x,
6x-16=14,
6x-16+16=14+16,
6x=30,
6x÷6=30÷6,
x=5;
(2)
×2012,
=
×(2011+1),
=
×2011+
×1,
=2010+
,
=2010
;
(3)(
+
)×8+
,
=
×8+
×8+
,
=5+
+
,
=5+(
+
),
=5+1,
=6;
(4)
×(
+
+
),
=
×(
+
),
=
×
,
=
;
(5)
×[1÷(
-
)],
=
×[1÷
],
=
×
,
=
.
8x-16=2x+14,
8x-16-2x=2x+14-2x,
6x-16=14,
6x-16+16=14+16,
6x=30,
6x÷6=30÷6,
x=5;
(2)
| 2010 |
| 2011 |
=
| 2010 |
| 2011 |
=
| 2010 |
| 2011 |
| 2010 |
| 2011 |
=2010+
| 2010 |
| 2011 |
=2010
| 2010 |
| 2011 |
(3)(
| 5 |
| 8 |
| 1 |
| 27 |
| 19 |
| 27 |
=
| 5 |
| 8 |
| 1 |
| 27 |
| 19 |
| 27 |
=5+
| 8 |
| 27 |
| 19 |
| 27 |
=5+(
| 8 |
| 27 |
| 19 |
| 27 |
=5+1,
=6;
(4)
| 3 |
| 5 |
| 1 |
| 7 |
| 8 |
| 21 |
| 2 |
| 3 |
=
| 3 |
| 5 |
| 11 |
| 21 |
| 2 |
| 3 |
=
| 3 |
| 5 |
| 25 |
| 21 |
=
| 5 |
| 7 |
(5)
| 1 |
| 6 |
| 3 |
| 5 |
| 3 |
| 10 |
=
| 1 |
| 6 |
| 3 |
| 10 |
=
| 1 |
| 6 |
| 10 |
| 3 |
=
| 5 |
| 9 |
点评:此题主要考查分的四则混合运算的运算顺序和应用运算定律进行简便计算.
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