解方程.(1)576÷x=2×9(2)13x+8.6-5x=36.2(3)6(x-0.3)=1.8(4)66.6-4x=55÷2(5)96-3(x-1.3)=15(6

发布时间:2020-08-09 00:45:11

解方程.
(1)576÷x=2×9
(2)13x+8.6-5x=36.2
(3)6(x-0.3)=1.8
(4)66.6-4x=55÷2
(5)96-3(x-1.3)=15
(6)2x+3x-29=4x.

网友回答

解:(1)576÷x=2×9
????? 576÷x×x=2×9×x
??????????? 576=18x
????????18x÷18=576÷18
????????????? x=32;

(2)13x+8.6-5x=36.2
13x+8.6-5x-8.6=36.2-8.6
????????????8x=27.6
???????? 8x÷8=27.6÷8
???????????? x=3.45;

(3)6(x-0.3)=1.8
? 6(x-0.3)÷6=1.8÷6
????????? x-0.3=0.3
????? x-0.3+0.3=0.3+0.6
????????????? x=0.6;

(4)66.6-4x=55÷2
? 66.6-4x+4x=55÷2+4x
?????? ?66.6=27.5+4x
???? 4x+27.5=66.6
4x-27.5-27.5=66.6-27.5
????????? 4x=39.1
?????? 4x÷4=39.1÷4
?????????? x=9.775;

(5)96-3(x-1.3)=15
96-3(x-1.3)+3(x-1.3)=15+3(x-1.3)
?????????????????????96=15+3(x-1.3)
???????????15+3(x-1.3)=96
??????? 15+3(x-1.3)-15=96-15
????????????? 3(x-1.3)=81
????????????? 3(x-1.3)=81
????????????? 3(x-1.3)=81
?????????? 3(x-1.3)÷3=81÷3
????????????? ??? x-1.3=27
???????????? ?x-1.3+1.3=27+1.3
????????????????? ??? x=28.3;
(6)2x+3x-29=4x
??????? 5x-29=4x
? 5x-29+29-4x=4x+29-4x
??????????? x=29.
解析分析:(1)根据等式的性质,方程两边都乘x,同时计算出9×2,方程变为576=18x,再把方程左右两边交换位置是18x=576,方程两边再除以18.
(2)先计算出方程左13x-5x,同时方程两边都减8.6,方程为8x=27.6,方程两边再都除以8.
(3)方程两边都除以6,方程变为x-0.3=0.3,方程两边都再加0.3.
(4)方程两边都加4x,同时计算出55÷2,方程变为66.6=27.5+4x,方程左、右交换位置,再减去27.5,此时方程是4x=39.1,方程两边再除以4即可.
(5)比较麻烦,方程两边都加3(x-1.3),方程变为 96=15+3(x-1.3),两边交换位置,方程变为 15+3(x-1.3)=96,方程两边都减15,方程变为3(x-1.3)=81,方程两边再都除以3,然后两边再都加1.3.
(6)方程两边都减4x,同时都加29即可.

点评:本题是考查解方程,注意书写格式,等号对齐,不能连等,同时注意口头验算.
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