题目内容
解方程
x-0.25x=3 | x+
|
3.6x÷2=2.16. |
分析:(1)原式变为(1-0.25)x=3,即0.75x=3,根据等式的性质,两边同除以0.75即可;
(2)原式变为(1+
)x=21,即1.4x=21,根据等式的性质,两边同除以1.4即可;
(3)根据等式的性质,两边同乘2,得3.6x=4.32,两边同除以3.6即可.
(2)原式变为(1+
2 |
5 |
(3)根据等式的性质,两边同乘2,得3.6x=4.32,两边同除以3.6即可.
解答:解:(1)x-0.25x=3,
(1-0.25)x=3,
0.75x=3,
0.75x÷0.75=3÷0.75,
x=4;
(2)x+
x=21,
(1+
)x=21,
1.4x=21,
1.4x÷1.4=21÷1.4,
x=15;
(3)3.6x÷2=2.16,
3.6x÷2×2=2.16×2,
3.6x=4.32,
3.6x÷3.6=4.32÷3.6,
x=1.2.
(1-0.25)x=3,
0.75x=3,
0.75x÷0.75=3÷0.75,
x=4;
(2)x+
2 |
5 |
(1+
2 |
5 |
1.4x=21,
1.4x÷1.4=21÷1.4,
x=15;
(3)3.6x÷2=2.16,
3.6x÷2×2=2.16×2,
3.6x=4.32,
3.6x÷3.6=4.32÷3.6,
x=1.2.
点评:在解方程时应根据等式的性质,即等式两边同加上、同减去、同乘上或同除以某一个数(0除外),等式的两边仍相等,同时注意“=”上下要对齐.
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