指数、对数方程与不等式,救救我,明天要交
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原式等价于: (lg2+lgx)*lgx-lg5=0 ===> (lgx)^+lg2*lgx-lg5=0 ===> (lgx)^+(lg[10/5])*lgx-lg5=0 ===> (lgx)^+(1-lg5)*lgx-lg5=0 ===> (lgx-lg5)(lgx+1)=0 ===> lgx=lg5或者lgx=-1 ===> x=5或者x=1/10
答:原式等价于: (2^x)^2-4*(2^x)+3=0 ===> [(2^x)-1][(2^x)-3]=0 ===> 2^x=1或者2^x=3 ===> x=0或...详情>>