f(x)=x^5+5x^4+5x^3+1求导得：f(x)=5x^4+20x^3+15x^2=5x^2(x^2+4x+3)=5x^2(x+3)(x+1)∵x＜-3时,f'(x)＞0,f(x)单调增-3＜x＜-1时,f'(x)＜0,f(x)单调减x＞-1时,f'(x)＞0,f(x)单调增∴x=-3时有极大值f(-3)=(-3)^5+5(-3)...