题目内容
解方程
4.5+2X=40.5 | 10.8-0.5X=4.8 | 0.5X-25=75. |
解:(1)4.5+2X=40.5,
4.5+2X-4.5=40.5-4.5,
2x=36,
2x÷2=36÷2,
x=18;
(2)10.8-0.5X=4.8,
10.8-0.5X+0.5x=4.8+0.5x,
10.8-4.8=4.8+0.5x-4.8,
6=0.5x,
6÷0.5=0.5x÷0.5,
x=12;
(3)0.5X-25=75,
0.5X-25+25=75+25,
0.5x=100,
0.5x÷0.5=100÷0.5,
x=200.
分析:(1)依据等式的性质,方程两边同时减4.5,再同时除以2求解;
(2)依据等式的性质,方程两边同时加0.5x,然后同时减4.8,最后同时除以0.5求解;
(3)依据等式的性质,方程两边同时加25,再同时除以0.5求解.
点评:解方程的依据是等式的性质,解方程时注意对齐等号.
4.5+2X-4.5=40.5-4.5,
2x=36,
2x÷2=36÷2,
x=18;
(2)10.8-0.5X=4.8,
10.8-0.5X+0.5x=4.8+0.5x,
10.8-4.8=4.8+0.5x-4.8,
6=0.5x,
6÷0.5=0.5x÷0.5,
x=12;
(3)0.5X-25=75,
0.5X-25+25=75+25,
0.5x=100,
0.5x÷0.5=100÷0.5,
x=200.
分析:(1)依据等式的性质,方程两边同时减4.5,再同时除以2求解;
(2)依据等式的性质,方程两边同时加0.5x,然后同时减4.8,最后同时除以0.5求解;
(3)依据等式的性质,方程两边同时加25,再同时除以0.5求解.
点评:解方程的依据是等式的性质,解方程时注意对齐等号.
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