解方程 4X-15.5=4.51-5X=0.45X+3X=1.6X-0.05X=5.75.6X+2.2=30.22X-2+8=48.
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解:(1)4X-15.5=4.5,
??? 4X-15.5+15.5=4.5+15.5,
????????????? 4x=20,
?????????? 4x÷4=20÷4,
?????????????? x=5;
(2)1-5X=0.4,
??1-5X+5x=0.4+5x,
??? 1-0.4=0.4+5x-0.4,
???0.6÷5=5x÷5,
??????? x=0.12;
(3)5X+3X=1.6,
??????? 8x=1.6,
???? 8x÷8=1.6÷8,
??????? x=0.2;
(4)X-0.05X=5.7,
?????? 0.95x=5.7,
?0.95x÷0.95=5.7÷0.95,
?????????? x=6;
(5)5.6X+2.2=30.2,
?5.6X+2.2-2.2=30.2-2.2,
???????? 5.6x=28,
??? 5.6x÷5.6=28÷5.6,
??????????? x=5;
(6)2X-2+8=48,
???? 2x+6-6=48-6,
???????? 2x=42,
????? 2x÷2=42÷2,
??????????x=21.
解析分析:(1)依据等式的性质,方程两边同时加15.5,再同时除以4求解,(2)依据等式的性质,方程两边同时加5x,再同时减0.4,最后同时除以5求解,(3)先化简方程,再依据等式的性质,方程两边同时除以8求解,(4)先化简方程,再依据等式的性质,方程两边同时除以0.95求解,(5)依据等式的性质,方程两边同时减2.2,再同时除以5.6求解,(6)先化简方程,再依据等式的性质,方程两边同时减6,最后同时除以2求解.
点评:解方程时要注意:(1)方程能化简先化简,(2)等号对齐.