首先计算-x²+2x+3的单调区间,-x²+2x+3=-x²+2x-1+4=-(x-1)^2+4根号下面的数值越大开出来的就越大,所以求-(x-1)^2+4的单调增区间就可以-(x-1)^2+4≥0,-1≤x≤3,函数f(x)=-(x-1)^2+4在[-1,1]单调递...