作业帮解以下方程17-x=210.8-x=2.5回答越快越好,只有10十分钟了,
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解以下方程17-x=210.8-x=2.5回答越快越好,只有10十分钟了,
解以下方程
17-x=2
10.8-x=2.5
回答越快越好,只有10十分钟了,
解以下方程17-x=210.8-x=2.5回答越快越好,只有10十分钟了,
17-x=2
x=17-2
x=15
10.8-x=2.5
x=10.8-2.5
x=8.3
看看solve这个命令。在matlab命令行上敲入：
solve('91.83/(2.07*(100-x)/x+1)+2.37/(0.359*(100-x)/x+1)+1.83/(0.084*(100-x)/x+1)+1.68/(0.0251*(100-x)/x+1)+1.32/(0.0075*(100-x)/x+1)+0.97/(0.00092*(100-x)/x+1)-x')
...
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看看solve这个命令。在matlab命令行上敲入：
solve('91.83/(2.07*(100-x)/x+1)+2.37/(0.359*(100-x)/x+1)+1.83/(0.084*(100-x)/x+1)+1.68/(0.0251*(100-x)/x+1)+1.32/(0.0075*(100-x)/x+1)+0.97/(0.00092*(100-x)/x+1)-x')
我看了结果是跟那两位的一样，得到7个解，不过x=0显然不是解，估计是matlab的BUG。
因0不能作分母。一个笨方法是逐个带入求解，有matlab函数subs可以解决。
如下：
xx=solve('91.83/(2.07*(100-x)/x+1)+2.37/(0.359*(100-x)/x+1)+1.83/(0.084*(100-x)/x+1)+1.68/(0.0251*(100-x)/x+1)+1.32/(0.0075*(100-x)/x+1)+0.97/(0.00092*(100-x)/x+1)-x')
xx =
9.5928722289771455041249312194069
-51.25070353762559926595511337666
100.0
-1.7631487189817605177017457928844
-7.4742012011826256018294334313148
-0.34893975376738034980285890672882
0
subs('91.83/(2.07*(100-x)/x+1)+2.37/(0.359*(100-x)/x+1)+1.83/(0.084*(100-x)/x+1)+1.68/(0.0251*(100-x)/x+1)+1.32/(0.0075*(100-x)/x+1)+0.97/(0.00092*(100-x)/x+1)-x','x',xx(1))
ans =
1.4541648269870039213039013706974*10^(-37)
>> subs('91.83/(2.07*(100-x)/x+1)+2.37/(0.359*(100-x)/x+1)+1.83/(0.084*(100-x)/x+1)+1.68/(0.0251*(100-x)/x+1)+1.32/(0.0075*(100-x)/x+1)+0.97/(0.00092*(100-x)/x+1)-x','x',xx(2))
ans =
(-1.2652826131748627602783043114906)*10^(-36)
>> subs('91.83/(2.07*(100-x)/x+1)+2.37/(0.359*(100-x)/x+1)+1.83/(0.084*(100-x)/x+1)+1.68/(0.0251*(100-x)/x+1)+1.32/(0.0075*(100-x)/x+1)+0.97/(0.00092*(100-x)/x+1)-x','x',xx(3))
ans =
1.0285575569695015694726444700695*10^(-38)
>> subs('91.83/(2.07*(100-x)/x+1)+2.37/(0.359*(100-x)/x+1)+1.83/(0.084*(100-x)/x+1)+1.68/(0.0251*(100-x)/x+1)+1.32/(0.0075*(100-x)/x+1)+0.97/(0.00092*(100-x)/x+1)-x','x',xx(4))
ans =
(-5.8344113438106212736497260726423)*10^(-40)
>> subs('91.83/(2.07*(100-x)/x+1)+2.37/(0.359*(100-x)/x+1)+1.83/(0.084*(100-x)/x+1)+1.68/(0.0251*(100-x)/x+1)+1.32/(0.0075*(100-x)/x+1)+0.97/(0.00092*(100-x)/x+1)-x','x',xx(5))
ans =
3.2984175096138360958310753236859*10^(-36)
>> subs('91.83/(2.07*(100-x)/x+1)+2.37/(0.359*(100-x)/x+1)+1.83/(0.084*(100-x)/x+1)+1.68/(0.0251*(100-x)/x+1)+1.32/(0.0075*(100-x)/x+1)+0.97/(0.00092*(100-x)/x+1)-x','x',xx(6))
ans =
2.8887019080459322775106987459902*10^(-41)
>> subs('91.83/(2.07*(100-x)/x+1)+2.37/(0.359*(100-x)/x+1)+1.83/(0.084*(100-x)/x+1)+1.68/(0.0251*(100-x)/x+1)+1.32/(0.0075*(100-x)/x+1)+0.97/(0.00092*(100-x)/x+1)-x','x',xx(7))
??? Error using ==> mupadfeval at 28
Error: Division by zero [_power];
during evaluation of 'mlsubs'
Error in ==> sym.subs at 219
G = sym(mupadfeval('mlsubs', charcmd(G), [x '=' charcmd(y)]));
最后带入0，出错了，因此是头6个解，看结果都已经到10的-30次方以下了，精度够了。
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