lg(x^2+1)-lg(x-2)>1lg(x^2+1)-lg(x-2)>12log25(X)+logx(25)>3

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lg(x^2+1)-lg(x-2)>1lg(x^2+1)-lg(x-2)>12log25(X)+logx(25)>3

lg(x^2+1)-lg(x-2)>1lg(x^2+1)-lg(x-2)>12log25(X)+logx(25)>3
lg(x^2+1)-lg(x-2)>1
lg(x^2+1)-lg(x-2)>1
2log25(X)+logx(25)>3

lg(x^2+1)-lg(x-2)>1lg(x^2+1)-lg(x-2)>12log25(X)+logx(25)>3
lg(x^2+1)-lg(x-2)>1
lg[(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)>0
23
2log25(X)+[1/log25(x)]>3
设log25(X)=t
2t^2-3t+1>0
t>1或t1
x>25
log25(X)

1、lg(x^2+1)-lg(x-2)>1
lg[(x^2+1)/(x-2)]>1
(x^2+1)/(x-2)>10
∵x^2+1》0
∴x-2>0 x>2
解得(x^2+1)/(x-2)>10
x>7或x<3
综上27
2)2log25(X)+logx(25)>3
2log25(X)+[1/log25(x)]>3
lgx/lg5+2lg5/lgx>3
解得x>25或0