设t=log2(2^x-1)则log2(2^(x+2)-4）=2+t原式=t*（2+t）=3t=-3ort=1log2(2^x-1)=-32^x-1=1/82^x=9/8x=2log2(3)-3log2(2^x-1)=12^x-1=22^x=3x=log2(3)综上x=2log2(3)-3 or x=log2(3)