試題詳解

15. Find a and b so that function f(x)=ax³+bx²+1 will have a relative minimum value at a point inside the open interval (1, 3).
(A) a =1, b =1
(B) a =1, b = −1
(C) a = −1, b =2
(D) a = 2, b = −4
(E) a = −1, b =3