Question

t=(2^x-1)/(2^x+1)在(-无穷,0)上有解,求t取值范围

Answer 1

已知t=[(2^x)-1]/[(2^x)+1],求t的取值范围.

去分母得t[(2^x)+1]=(2^x)-1；即有(t-1)(2^x)=-t-1,故得2^x=-(t+1)/(t-1)；

于是得x=log₂[-(t+1)/(t-1)]

由-(t+1)/(t-1)>0,得(t+1)/(t-1)