6.2X-X=41.6????????2X+1.3×4=6.8???????19.5÷3X=2.

发布时间:2020-07-31 15:41:30

6.2X-X=41.6????????2X+1.3×4=6.8???????19.5÷3X=2.

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解:(1)6.2X-X=41.6,
???? (6.2-1)X=41.6,
???????????5.2X=41.6,
????? 5.2X÷5.2=41.6÷5.2,
????????????? X=8;

(2)2X+1.3×4=6.8,
??????? 2X+5.2=6.8,
??? 2X+5.2-5.2=6.8-5.2,
??????????? 2X=1.6,
???????? 2X÷2=1.6÷2,
???????????? X=0.8;

(3)19.5÷3X=2,
?19.5÷3X×3X=2×3X,
?????????19.5=6X,
??????? 6X÷6=19.5÷6,
??????????? X=3.25.

解析分析:(1)根据乘法分配律的逆运算,原式变为 (6.2-1)X=41.6,即5.2X=41.6,根据等式的性质,两边同除以5.2即可;(2)先算出1.3×4=5.2,原式变为2X+5.2=6.8,根据等式的性质,两边同减去5.2,再同除以2即可;(3)根据等式的性质,两边同乘3X,变为19.5=6X,即6X=19.5,两边同除以6即可.

点评:此题考查了根据等式的性质解方程,即方程两边同加、同减、同乘或同除以某数(0除外),方程的左右两边仍相等;注意“=”号上下要对齐.
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