没有错解题如下y=(x-20) [50-1/10(x-180)]=（x-20)(680-x)/10=(-x²+700x-13600)/10=-(x²-700x+13600)/10=-[(x-350)²-108900]/10=-(x-350)²/10+10890当定价为350元时,利润最大,最大为10890元.不...我计算是这样的y=(x-20) [50-1/10(x-180)] =(x-20)(-1/10x+32) =-1/10x²+34x-640 =-1/10(x²-340x)-640 =-1/10[(x-170)²-170²]-640你哪个计算我看不懂。。我这个哪里算错了。。y=(x-20) [50-1/10(x-180)] =(x-20)(-1/10x+32)这一步你就错了是=（x-20)(-1/10x+68)你再看看我的算法y=(x-20) [50-1/10(x-180)]=（x-20)(680-x)/10是将中括号通分，提取1/10