20. (2022秋•衡水月考)已知函数f(x)=xln(2x−1)+4xf(x)=xln(2x-1)+\frac{4}{x}f(x)=xln(2x−1)+x4,则曲线y=f(x)y=f(x)y=f(x)在点(1(1(1,fff(1))))处的切线方程为 ___2x+y−6=02x+y-6=02x+y−6=0___.