1.若a=1/2,求方程f（x）+2=0即log1/2(1/2x-√x) =-21/2x-√x=4x=1/4x^2-4x+16x^2-20x+64=0,x1=4,x2=161/2x-√x>0,x=\4x=162.若函数f（x）在（2,+∞）单调递减,求a的取值范围设√x=b>0,ab^2-b,对称轴为1/2aa>0,必有ab...