lg(x^2+1)-lg(x-2)>1lg[(x^2+1)/(x-2)]>1(x^2+1)/(x-2)>10(x^2-10x+21)/(x-2)>0(x-3)(x-7)(x-2)>0232log25(X)+[1/log25(x)]>3设log25(X)=t2t^2-3t+1>0t>1或t1x>25log25(X)