设价格提高X元,利润是Y
Y=(2+X)[100-(X/0.5)*50]=(2+X)(100-100X)=200-200X+100X-100X^2
=-100X^2-100X+200
=-100(X^2+X)+200
=-100(X+0.5)^2+225
即当X=-0.5时,Y有最大值.是225
所以,应该是价格下降0.5元时利润最大.
选:第四个.
设价格提高X元,利润是Y
Y=(2+X)[100-(X/0.5)*50]=(2+X)(100-100X)=200-200X+100X-100X^2
=-100X^2-100X+200
=-100(X^2+X)+200
=-100(X+0.5)^2+225
即当X=-0.5时,Y有最大值.是225
所以,应该是价格下降0.5元时利润最大.
选:第四个.