The function f (x) = 2x3 – 3x2 – 12x + 4, has
Let f(x)= 2x3 – 3x2 – 12x + 4
Applying the first derivative we get
Applying the sum rule of differentiation, so we get
Applying the derivative,
⇒ f' (x)=6x2-6x-12
Putting f’(x)=0,we get critical points as
6x2-6x-12=0
⇒ 6(x2-x-2)=80
⇒ x2-x-2=0
Splitting the middle term we get
⇒ x2-2x+x-2=0
⇒ x(x-2)+1(x-2)=0
⇒ (x-2)(x+1)=0
⇒ x-2=0 or x+1=0
⇒ x=2 or x=-1
Now we will find the value of f(x) at x=-1, 2
f(x)= 2x3 – 3x2 – 12x + 4
f(-1)= 2(-1)3 – 3(-1)2 – 12(-1) + 4=-2-3+12+4=11
f(2)= 2(2)3 – 3(2)2 – 12(2) + 4 =16-12-24+4=-16
Hence from above we find that x=-1 is point of local maxima and the maximum value of f(x) is 11.
Whereas x=2 is point of local minima and the minimum value of f(x) is -16.
So the correct option is option C.
Hence the given function 2x3 – 3x2 – 12x + 4has one maxima and one minima