这就讨论下x的取值,1.当x+1≥0,(x≥-1)x+(x+1)f(x+1)≤1x+(x+1)(x+1-1)≤1x+x(x+1)≤1x^2+2x-1≤0-1≤x≤-1+√22.x+1＜0,(x＜-1)x+(x+1)f(x+1)≤1x+(x+1)[-(x+1)+1]≤1-x^2≤1x+(x+1)f(x+1)