A:C2H5OH
B:CH3COOH
C:CH3CHO
D:C6H5OH
(Ⅰ)求函数f(x)的最小值;
(Ⅱ)若f(x)<ax+1有解,求实数a的取值范围.
已知x ,y满足条件x-y+5≥0x+y≥0x≤3则z=y-1x+3的最大值( )