Question

find the point of minima of y=x3-12x-5​

Answer 1

Answer:

f(x)=−x2+12x2−5

f′(x)=−3x2+24x=0

x2−8x=0

x(x−8)=0 ⇒ x=0 or x=8

f′(x)=−6x+24

f11(x)=24>0f11(8)=−48+24=−24<0

⇒ x=0 is minimum x=8 is maximum