已知函数f(x)=2的x次方 1&
用2^x表示2的x次方y=[2^x+1]/[2^x-1] 【设:2^x=t,则:t>0】y=(t+1)/(t-1)yt-y=t+1(y-1)t=y+1t=(y+1)/(y-1)因为:t>0,则:(y+1)/(y-1)>0,得:y>1或yy=[2^x+1]/[2^x-1]=[(2^x-1)+2]/[2^x-1]=1+2/[2^x-1]函数在(-∞,0)上递减,在(0,+∞)上递减。
用2^x表示2的x次方y=[2^x+1]/[2^x-1] 【设:2^x=t,则:t>0】y=(t+1)/(t-1)yt-y=t+1(y-1)t=y+1t=(y+1)/(y-1)因为:t>0,则:(y+1)/(y-1)>0,得:y>1或yy=[2^x+1]/[2^x-1]=[(2^x-1)+2]/[2^x-1]=1+2/[2^x-1]函数在(-∞,0)上递减,在(0,+∞)上递减。
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