解比例或方程:
①??????????????
②12÷(0.5x-1)=6.
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解:(1),
?3.5×(x-16)=1.5x,
?????? 3.5x-56=1.5x,
? 3.5x-56-1.5x=1.5x-1.5x,
????? 2x-56+56=56,
???????? 2x÷2=56÷2,
???????????? x=28;
(2)12÷(0.5x-1)=6,
12÷(0.5x-1)×(0.5x-1)=6×(0.5x-1),
??????????????????????? 12=3x-6,
??????????????????????12+6=3x-6+6,
?????????????????????18÷3=3x÷3,
???????????????????????? x=6.
解析分析:(1)先根据比例的基本性质,把原式转化为3.5×(x-16)=1.5x,再化简,然后根据等式的性质,在方程两边同时减去1.5x,再加上56,最后除以2求解,
(2)先化简,再根据等式的性质,在方程两边同时乘上(0.5x-1),再化简,然后加上6,再除以3求解.
点评:本题考查了学生根据等式的性质和比例的基本性质解方程的能力,注意等号对齐.