What are the points of inflection, if any, of #f(x) =12x^5+15x^4–240x^3+6#?

Answer 1

The points of inflection are at:
#x=0,(-3+-sqrt(393))/8#

The points of inflection are given by when #f''(x)=0#.
#f(x)=12x^5+15x^4-240x^3+6# #f'(x) =60x^4+60x^3-720x^2# #f''(x)=240x^3+180x^2-1440x#
#x=60x(4x^2+3x-24)# (1) #60x=0# #x=0#
(2) and (3) #4x^2+3x-24=0# #x=(-3+-sqrt(393))/8#
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Answer 2

To find the points of inflection of ( f(x) = 12x^5 + 15x^4 - 240x^3 + 6 ), we first need to find its second derivative, ( f''(x) ). Then, we find the values of ( x ) where ( f''(x) = 0 ) or ( f''(x) ) does not exist. These values will be the potential points of inflection. After that, we check the concavity of the function around these points to confirm if they are indeed points of inflection.

First derivative of ( f(x) ): [ f'(x) = 60x^4 + 60x^3 - 720x^2 ]

Second derivative of ( f(x) ): [ f''(x) = 240x^3 + 180x^2 - 1440x ]

Now, set ( f''(x) = 0 ): [ 240x^3 + 180x^2 - 1440x = 0 ] [ 60x(x^2 + 3x - 24) = 0 ] [ 60x(x + 6)(x - 4) = 0 ]

This gives us potential points of inflection at ( x = 0, x = -6, ) and ( x = 4 ).

Now, we check the concavity of ( f(x) ) around these points:

  1. For ( x = 0 ): Substitute ( x = 0 ) into ( f''(x) ) to find the concavity: [ f''(0) = 0 + 0 - 0 = 0 ] So, ( x = 0 ) is a point of inflection.

  2. For ( x = -6 ): Substitute ( x = -6 ) into ( f''(x) ) to find the concavity: [ f''(-6) = -1440(-6) < 0 ] So, ( x = -6 ) is a point of inflection.

  3. For ( x = 4 ): Substitute ( x = 4 ) into ( f''(x) ) to find the concavity: [ f''(4) = 240(4)^3 + 180(4)^2 - 1440(4) > 0 ] So, ( x = 4 ) is a point of inflection.

Therefore, the points of inflection for the function ( f(x) = 12x^5 + 15x^4 - 240x^3 + 6 ) are ( x = 0, x = -6, ) and ( x = 4 ).

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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