题目内容
(2010?海安县)解下列方程.
=
x+
x=
7x-2×1.4=5.6.
| 0.1 |
| x |
| 0.25 |
| 0.125 |
x+
| 1 |
| 5 |
| 12 |
| 25 |
7x-2×1.4=5.6.
分析:(1)先根据比例的基本性质,把原式转化为0.25x=0.1×0.125,再根据等式的性质,在方程两边同时除以0.25来解.
(2)先化简,再根据等式的性质,在方程两边同时除以
来解.
(3)先化简,再根据等式的性质,在方程两边同时加上2.8,再除以7来解.
(2)先化简,再根据等式的性质,在方程两边同时除以
| 6 |
| 5 |
(3)先化简,再根据等式的性质,在方程两边同时加上2.8,再除以7来解.
解答:解:(1)
=
,
0.25x=0.1×0.125,
0.25x÷0.25=0.0125÷0.25,
x=0.05;
(2)x+
x=
,
x=
,
x÷
=
÷
,
x=
;
(3)7x-2×1.4=5.6,
7x-2.8=5.6,
7x-2.8+2.8=5.6+2.8,
7x÷7=8.4÷7,
x=1.2.
| 0.1 |
| x |
| 0.25 |
| 0.125 |
0.25x=0.1×0.125,
0.25x÷0.25=0.0125÷0.25,
x=0.05;
(2)x+
| 1 |
| 5 |
| 12 |
| 25 |
| 6 |
| 5 |
| 12 |
| 25 |
| 6 |
| 5 |
| 6 |
| 5 |
| 12 |
| 25 |
| 6 |
| 5 |
x=
| 2 |
| 5 |
(3)7x-2×1.4=5.6,
7x-2.8=5.6,
7x-2.8+2.8=5.6+2.8,
7x÷7=8.4÷7,
x=1.2.
点评:本题考查学生根据比例的基本性质和等式的性质解方程的能力,注意等号要对齐.
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