设\(f(x)\)存在导函数，且满足\(\overset\lim{∆x→0} \dfrac{f\left(1\right)-f\left(1-2∆x\right)}{2∆x}=-1 \)，则曲线\(y=f(x)\)上点\((1,f(1))\)处的切线斜率为  \((\)    \()\)