For the following function. Use algebra to find all critical and inflection points. Use algebra to identify local and global maxima and minima f in the interval. Use your graphical calculator or Desmos to confirm your answer  f (x) = x3 - 3x2 (-1 ≤ x ≤ 3)

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Problem 31RE: For the following exercises, use the graphs to determine the intervals on which the functions are...
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For the following function. Use algebra to find all critical and inflection points. Use algebra to identify local and global maxima and minima in the interval. Use your graphical calculator or Desmos to confirm your answer 

f (x) = x3 - 3x(-1 ≤ x ≤ 3)

Expert Solution
Step 1

Given function is

fx=x3-3x2-1x3

Step 2: To find the critical points

fx=x3-3x2

Differentiate with respect to x,

f'x=3x2-6x

To find the critical points, take f'x=0

3x2-6x=03xx-2=03x=0  or  x-2=0x=0    or        x=2

As it is polynomial function, the domain of fx is -, 

Also, 0, 2-,  and 0, 2-1, 3

Hence, the critical points are x=-1, 0, 2, 3

Step 3

f'x=3x2-6x

Differentiate f'x with respect to x to find second derivative of fx

f''x=6x-6=6x-1

Critical point Value of f''x Maximum/Minimum
x=0 f''0=60-6=-6<0 So, is local maximum.
x=2 f''2=62-6=12-6=6>0 So, is local minimum.
x=3 f''2=63-6=18-6=12>0 So, is global minimum.
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