举报
47996966
嗯,后面的判断错了点,更正如下: 由y<=x-1, y>=1/4x-7/4-->1/4x-7/4<=x-1--> x>=-1 y<=-2x+5, y>=1/4x-7/4-->1/4x-7/4<=-2x+5-->x<=3, 因此有: -1= y=z+2x y<=x-1--> z+2x<=x-1-->z<=-x-1--> z<=1-1=0 y<=-2x+5--> z+2x<=-2x+5--> z<=-4x+5--> z<=4+5=9 y>=1/4x-7/4--> z+2x>=1/4x-7/4--> z>=-7x/4-7/4--> z>=-7(*3)/4-7/4=-7 即有:z<=0, z<=9, z>=-7 所以只能取三者的交集:-7=