1.当单价为x时,年销量会减少1000(x-50),所以有 y=200000-1000(x-50)即 y=150000-1000x2.年利润z=(x-20)y=1000(150-x)(x-20),所以当z=1200000时,有(150-x)(x-20)=1200, 解上式得：x=30 或 x=140 由...