赞 共回答了16个问题采纳率：93.8% 举报
f(x) = 3ax^4-2(3a+1)x^2+4x
a= 1/6
f(x) = (1/2)x^4-3x^2+4x
f'(x) = 2x^3-6x+4
f'(x) =0
2x^3-6x+4=0
2(x-1)(x^2+x-2)=0
(x-1)^2.(x+2)=0
x=1 or -2
f''(x) = 6x^2-6
f''(1) =0
f''(-2) = 18 > 0 ( min )
min f(x) at x=-2
f(-2) = 8-12-8 =-12
a= 1/6
f(x) = (1/2)x^4-3x^2+4x
f'(x) = 2x^3-6x+4
f'(x) =0
2x^3-6x+4=0
2(x-1)(x^2+x-2)=0
(x-1)^2.(x+2)=0
x=1 or -2
f''(x) = 6x^2-6
f''(1) =0
f''(-2) = 18 > 0 ( min )
min f(x) at x=-2
f(-2) = 8-12-8 =-12
1年前
3
可能相似的问题
-
已知函数f(x)=3ax 4 -2(3a+1)x 2 +4x，
1年前1个回答
-
1已知函数.f(x)=3ax^4-2(3a+1)x^2+4x
1年前5个回答
-
1年前1个回答
-
1已知函数.f(x)=3ax^4-2(3a+1)x^2+4x
1年前3个回答
-
1年前1个回答
你能帮帮他们吗