1
f'(x)=3x^2+2ax-1
f'(2/3)=4/3+4/3a-1=a ==> a=-1
(2)f'(x)=3x^2-2x-1 =3(x-1)(x+1/3)
f'(x)>0 ==> x1
f'(x) -1/30,f(x)递增,
f(x)min=f(1)=1,不合题意
1
高中导函数大题难题 求解 急用 我采纳!
a=-1(2)f'(x)=3x^2-2x-1 =3(x-1)(x+"}}}'>
1
f'(x)=3x^2+2ax-1
f'(2/3)=4/3+4/3a-1=a ==> a=-1
(2)f'(x)=3x^2-2x-1 =3(x-1)(x+1/3)
f'(x)>0 ==> x1
f'(x) -1/30,f(x)递增,
f(x)min=f(1)=1,不合题意
1