解方程:x+3.2=10.83x÷13=209x-36=5x2.5×3-2x=0.54(2-x)=1x÷1.7-0.8=6.

发布时间:2020-07-31 04:03:34

解方程:x+3.2=10.83x÷13=209x-36=5x2.5×3-2x=0.54(2-x)=1x÷1.7-0.8=6.

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解:(1)x+3.2=10.83,
???? x+3.2-3.2=10.83-3.2,
???????????? x=7.63;

(2)x÷13=20,
?x÷13×13=20×13,
???????? x=260;

(3)9x-36-5x=5x-5x,
????????4x-36=0,
???? 4x-36+36=0+36,
?????????? 4x=36,
??????? 4x÷4=36÷4,
??????????? x=9;

(4)2.5×3-2x=0.5,
??????? 7.5-2x=0.5,
???? 7.5-2x+2x=0.5+2x,
??????? 0.5+2x=7.5,
??? 0.5+2x-0.5=7.5-0.5,
??????????? 2x=7,
???????? 2x÷2=7÷2,
?????????????x=3.5;

(5)4(2-x)=1,
???????? 8-4x=1,
????? 8-4x+4x=1+4x,
???????? 1+4x=8,
?????? 1+4x-1=8-1,
?????????? 4x=7,
????????4x÷4=7÷4,
??????????? x=;

(6)x÷1.7-0.8=6,
?x÷1.7-0.8+0.8=6+0.8,
???????? x÷1.7=6.8,
??? x÷1.7×1.7=6.8×1.7,
??????????????x=11.56.
解析分析:(1)根据等式的性质,两边同减去3.2即可;(2)根据等式的性质,两边同乘13即可;(3)根据等式的性质,两边同减去5x,得4x-36=0,两边同加上36,再同除以4即可;(4)原式变为7.5-2x=0.5,根据等式的性质,两边同加上2x,得0.5+2x=7.5,两边同减去0.5,再同除以2即可;(5)原式变为 8-4x=1,根据等式的性质,两边同加上4x,得1+4x=8,两边同减去1,再同除以4即可;(6)根据等式的性质,两边同加上0.8,得x÷1.7=6.8,两边再同乘1.7即可.

点评:此题考查了运用等式的性质解方程,即等式两边同加上或同减去、同乘上或同除以一个数(0除外),两边仍相等,同时注意“=”上下要对齐.
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