答案:(1)任取x1<x2,则f(x1)-f(x2)=log2(2x1+1)-log2(2x2+1)=log22x1+12x2+1,∵x1<x2,∴0<2x1+1<2x2+1,∴0<2x1+12x2+1<1,log22x1+12x2+1<0,∴f(x1)<f(x2),即函数f(x)在(-∞,+∞)内单调递增(2)∵f-1(x)=log2(2x-1)(x>0),∴m=f-1(x)-f(x)=log2(2x-1)-log2(2x+1)=log22x-12x+1=log2(1-22x+1)当1≤x≤2时,25≤22x+1≤23,∴13≤1-22x+1≤35∴m的取值范围是[log2(13),log2(35)]