給出下列四個命題:①當(dāng)f′(x₀)=0時，則f(x₀)為f(x)的極大值;②當(dāng)f′(x₀)=0時，則f(x₀)為f(x)的極小值;③當(dāng)f′(x₀)=0時，則f(x₀)為f(x)的極值;④當(dāng)f(x₀)為函數(shù)f(x)的極值時，則有    f′(x₀)=0.

其中正確命題的個數(shù)是

A.1                                                                 B.2

C.3                                                                 D.0

A.必有f′(x₀)=0                                    B.f′(x₀)的導(dǎo)數(shù)不存在

C.f′(x₀)=0或f′(x₀)不存在                    D.f′(x₀)存在但可能不為0

下列說法正確的是( )

1. A.
   當(dāng)f′(x₀)=0時，則f(x₀)為f(x)的極大值
2. B.
   當(dāng)f′(x₀)=0時，則為f(x₀)為f(x)的f(x)極小值
3. C.
   當(dāng)f′(x₀)=0時，則f(x₀)為f(x)的f(x)極值
4. D.
   當(dāng)f′(x₀為函數(shù)f(x)的極值且f′(x₀)存在時，則有f′(x₀)=0

A.當(dāng)f′(x₀)=0時，則f(x₀)為f(x)的極大值

B.當(dāng)f′(x₀)=0時，則f(x₀)為f(x)的極小值

C.當(dāng)f′(x₀)=0時，則f(x₀)為f(x)的極值

D.當(dāng)f(x₀)為函數(shù)f(x)的極值且f′(x₀)存在時，則有f′(x₀)=0

給出下列四個命題:
①當(dāng)f′(x₀)=0時，則f(x₀)為f(x)的極大值;
②當(dāng)f′(x₀)=0時，則f(x₀)為f(x)的極小值;
③當(dāng)f′(x₀)=0時，則f(x₀)為f(x)的極值;
④當(dāng)f(x₀)為函數(shù)f(x)的極值時，

則有   f′(x₀)=0.其中正確命題的個數(shù)是

1. A.
   1
2. B.
   2
3. C.
   3
4. D.
   0