已知函数f（x）＝3ax^4－2（3x+1）x^2＋4x,当a＝1／6时,求f（x）的极值

应该是f（x）＝3ax^4－2（3a+1）x^2＋4xa=1/6f(x)=x^4/2-3x²+4xf'(x)=2x³-6x+4=0x³-3x+2=0(x³-1)-3x+3=0(x-1)(x²+x+1)-3(x-1)=0(x-1)(x²+x-2)=0(x-1)²(x+2)=0x=1,x=-2f'(x)>=0时...