已知函数 f(x)=a(x−x1)(x−x2)(x−x3)(a>0)f\left( x\right) = a\left( {x - {x}_{1}}\right) \left( {x - {x}_{2}}\right) \left( {x - {x}_{3}}\right) \left( {a > 0}\right)f(x)=a(x−x1)(x−x2)(x−x3)(a>0) ，设曲线 y=f(x)y = f\left( x\right)y=f(x) 在点 (xi,f(xi))\left( {{x}_{i},f\left( {x}_{i}\right) }\right)(xi,f(xi)) 处切线的斜率为 ki(i=1,2,3){k}_{i}\left( {i = 1,2,3}\right)ki(i=1,2,3) ，若 x1,x2,x3{x}_{1},{x}_{2},{x}_{3}x1,x2,x3 均不相等，且 k2=−2{k}_{2} = - 2k2=−2 ，则 k1+4k3{k}_{1} + 4{k}_{3}k1+4k3 的最小值为___.