题目内容
解比例和方程.
75:x=25:15 | 24%x+8%x=16 | 1.8:x=![]() ![]() | ![]() ![]() |
解:(1)75:x=25:15,
25x=75×15,
25x÷25=1125÷25,
x=45;
(2)24%x+8%x=16,
32%x=16,
32%x÷32%=16÷32%,
x=50;
(3)1.8:x=
:
,
x=1.8×
,
x
=
,
x=
;
(4)
=
,
0.5x=0.25×2,
0.5x÷0.5=0.5÷0.5,
x=1.
分析:(1)根据比例基本性质:两内项之积等于两外项之积,化简方程,再依据等式的性质,方程两边同时除以25求解;
(2)先化简方程,再依据等式的性质,方程两边同时除以32%求解;
(3)根据比例基本性质:两内项之积等于两外项之积,化简方程,再依据等式的性质,方程两边同时除以
求解;
(4)根据比例基本性质:两内项之积等于两外项之积,化简方程,再依据等式的性质,方程两边同时除以0.5求解.
点评:等式的性质,以及比例基本性质是解方程的依据,解答时注意(1)方程能化简先化简,(2)等号要对齐.
25x=75×15,
25x÷25=1125÷25,
x=45;
(2)24%x+8%x=16,
32%x=16,
32%x÷32%=16÷32%,
x=50;
(3)1.8:x=
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x=

(4)
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0.5x=0.25×2,
0.5x÷0.5=0.5÷0.5,
x=1.
分析:(1)根据比例基本性质:两内项之积等于两外项之积,化简方程,再依据等式的性质,方程两边同时除以25求解;
(2)先化简方程,再依据等式的性质,方程两边同时除以32%求解;
(3)根据比例基本性质:两内项之积等于两外项之积,化简方程,再依据等式的性质,方程两边同时除以

(4)根据比例基本性质:两内项之积等于两外项之积,化简方程,再依据等式的性质,方程两边同时除以0.5求解.
点评:等式的性质,以及比例基本性质是解方程的依据,解答时注意(1)方程能化简先化简,(2)等号要对齐.

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