20. (2023春•凉山州期末)已知函数f(x)=x3+ax2+x+1f(x)=x^{3}+ax^{2}+x+1f(x)=x3+ax2+x+1在x=−1x=-1x=−1时取得极值.(1)求f(x)f(x)f(x)在(0(0(0,f(0))f(0))f(0))处的切线方程;(2)求f(x)f(x)f(x)在区间[−2[-2[−2,0]0]0]上的最大值与最小值.