数学题,要过程,谢谢!

2024-12-02 10:48:13
推荐回答(2个)
回答1:

解题思路 先明确 80%浓度的酒精是80ML的酒精和20ML的水 然后水和酒精互溶 倒走的是水和酒精 倒回来只有同体积的水 最后还剩下51.2%的酒精 相当于剩下51.2ML的酒精 和48,8ML的水
酒精少了28.8ML 按照酒精的比例0.8 得出28.8/0.8=36ML

我觉得应该是对的 而楼上错了 按照C=V1/(V1+V2) 也能很好算 因为液体一直是瞒的也就是100ML
所以C2=(80-0.8X)/100
按照楼上的思路 应该是C2=(80-0.8X)/(80-0.8X)+(20-0.2X + X) 化简就是上面的
请采纳

回答2:

解:设每次倒出x毫升溶液,
[(100-x)/100]²×80%=51.2%,
[(100-x)/100]²=0.64
(100-x)/100=±0.8
100-x=±80
x1=20,x2=180(舍去),
即每次倒出20毫升的溶液。

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