选煤厂设计和生产管理中,常须确定精煤的最适宜灰分,以便获得最大产值。这里精煤灰分相当于生产条件x,产值相当于管理目标y。这里产值和灰分不是直接而是通过精煤产率和精煤价格相联系的。如以y表示洗选一吨原煤所得的产值(元),以Y表示精煤产率(%),以U表示精煤价格(元/吨),则 Coal preparation plant design and production management, often need to determine the most suitable ash coal, in order to obtain the maximum output value. Here the equivalent of fine coal ash production conditions x, the output value is equivalent to the management goal y. The output value and ash content are not directly linked here but through the production of clean coal and the price of refined coal. If y represents the output value of a ton of raw coal washing (yuan), the yield of refined coal Y (%), the price of refined coal U (yuan / ton), then