What are the points of inflection of #f(x)=8x^2 + sin(2x-pi) # on # x in [0, 2pi]#?

Answer 1

None. No points of inflection.

Points of inflection are slope extrema or #f'(x)# extrema. To find a maximum or minimum, take the second derivative and set equal to zero, to find where change in slope is zero.
#f(x)=8x^2+sin(2x-pi)# #f'(x)=16x + 2cos(2x-pi)# #f''(x)=16 - 4sin(2x-pi)#
Now set #f''(x)=0#:
#0=16-4sin(2x-pi)# #-16=-4sin(2x-pi)# #4=sin(2x-pi)# #sin^-1(4)=2x-pi# #->#NO SOLUTION

Since sin(x) cannot be greater than 1, there are no (true, I'm not sure about complex) solutions.

As a result, there are no turning points.

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Answer 2

To find the points of inflection of ( f(x) = 8x^2 + \sin(2x - \pi) ) on ( x ) in the interval ([0, 2\pi]), follow these steps:

  1. Find the second derivative of the function ( f(x) ).
  2. Set the second derivative equal to zero and solve for ( x ).
  3. Determine the values of ( x ) that make the second derivative undefined (if any).
  4. Test the concavity of the function around each critical point to determine whether they are points of inflection.

Let's go through each step:

  1. Find the second derivative: [ f''(x) = 16 - 2\cos(2x - \pi) ]

  2. Set the second derivative equal to zero and solve for ( x ): [ 16 - 2\cos(2x - \pi) = 0 ] [ \cos(2x - \pi) = 8 ]

  3. Determine if there are any values of ( x ) that make the second derivative undefined. In this case, there are none.

  4. Test the concavity around each critical point by evaluating the second derivative at intervals in the given range:

For ( 0 \leq x < \frac{\pi}{2} ): [ f''(x) = 16 - 2\cos(2x - \pi) > 0 ]

For ( \frac{\pi}{2} < x \leq \pi ): [ f''(x) = 16 - 2\cos(2x - \pi) < 0 ]

For ( \pi \leq x < \frac{3\pi}{2} ): [ f''(x) = 16 - 2\cos(2x - \pi) > 0 ]

For ( \frac{3\pi}{2} < x \leq 2\pi ): [ f''(x) = 16 - 2\cos(2x - \pi) < 0 ]

Therefore, the points of inflection occur at the critical points where ( \cos(2x - \pi) = 8 ). These points are within the intervals ( 0 \leq x < \frac{\pi}{2} ), ( \pi \leq x < \frac{3\pi}{2} ). To find the exact values of these points, you need to solve ( \cos(2x - \pi) = 8 ) within these intervals.

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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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