Question

2. If f(x) = x^3 – 2x^2 – 24x, find f(-2). ​

Answer 1

Step-by-step explanation:

Answer

Given,

f(x)=2x

3

−24x+7

f

′

(x)=6x

2

−24

put f

′

(x)=0, for critical points

i.e., 6x

2

−24=0

x

2

−4=0

x=±2

Clearly, f

′

(x)>0 if x>2 & x<−2

f

′

(x)<0 if −2<x<2

Thus, f(x) is increasing in (−∞,−2)∪(2,∞), decreasing in (−2,2).

Answer 2

Step-by-step explanation:

f(2)= (-2)³-2×(-2)²-24×(-2)

-8 -2×4 + 48

-8+8+48=48