4/1是4分之1吧?y=sin²x+√3cosx+1/4=1-cos²x+√3cosx+1/4=-cos²x+√3cosx+5/4=-(cos²x-√3cosx+3/4)+3/4+5/4=-(cosx-√3/2)²+2∵ -1≤cosx≤1∴-1-√3/2≤cosx-√3/2≤1-√3/2则0≤(cosx-...