f(x)=x^3-mx^2-m^2x+m^3/27
f'(x)=3x²-2mx-m²=(x-m)(3x+m)
令f'(x)=0解得
x1=-m/3,x2=m ,m>3/4,
(-∞,-m/3)时,f'(x)>0,f(x)递增
(-m/3,m))时,f'(x)
f(x)=x^3-mx^2-m^2x+m^3/27
f'(x)=3x²-2mx-m²=(x-m)(3x+m)
令f'(x)=0解得
x1=-m/3,x2=m ,m>3/4,
(-∞,-m/3)时,f'(x)>0,f(x)递增
(-m/3,m))时,f'(x)