已知r 满足[r+19/100]+[r+20/100]+[r+21/100]+...+[r+91/100]=546.求[100r]的值?
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已知r 满足[r+19/100]+[r+20/100]+[r+21/100]+...+[r+91/100]=546.求[100r]的值?
已知r 满足[r+19/100]+[r+20/100]+[r+21/100]+...+[r+91/100]=546.求[100r]的值?
已知r 满足[r+19/100]+[r+20/100]+[r+21/100]+...+[r+91/100]=546.求[100r]的值?
91-19+1=73
一共73项
546/73=7.48
所以73项中有的是7,有的是8
设等于7的有x项,则等于8的有73-x项
则7x+8(73-x)=546
x=38
第38项=[r+56/100]=7
第39项=[r+57/100]=8
所以r+0.56=8
7.43
(91-19+1)r+[(19+91)*(91-19+1)/2]/100=546
73r+4015/100=546
100r=(54600-4015)/73=50585/73
好像不能整除
等式两边同时乘以100:
7300R+((19+91)/2)×73=54600
所以7300R=54600-4015=50585
100R=50585/73=692.94521