What are the points of inflection, if any, of #f(x)=x^3 - 12x^2 #?

Answer 1

#The# point of inflexion (POI) is ( 4, -`128 ). I could not drag the graph to #y < -90#, tosee the POI that is far down below.

#y=x^3-12x^2=x^2(x-12)=0#, for x = 0 and x = 12.
#y'=3x^2-24x=3x(x-8)=0#, for x = 0 and x = 8.

The first point is (0, 0). The second is far away. These are turning points.

down at #(8, -256)#, to rise for #y to oo, as x to oo#, through (12, 0)..

#y''=6x-24=0, for x = 4. This point ( 4, -128) is a candidate for point of

inflexion (POI).

#y'''= 6. y''' not 0 when y'' = 0 is a sufficient condition,

for the POI to be this point (4, -128).

Of course, as #x to -oo, y to -oo#.

Employing the contracting scale 1 for 20 for y only and 1 for 2 in x,

this POI and additional characteristics not shown by this graph,

could be revealed from concealment.

This edition, I was able to achieve contraction in a different graph (the

) to expose additional features. However, for the POI (point of

inllexion ) location, local zooming has to be made at #(4, -128)#.

graph{y=x^3-12x^2 [-9.915, 10.085, -9.52, 0.48]} and graph{y=x^3-12x^2 [-324.5, 324.5, -166.8, 157.7]}

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Answer 2

To find the points of inflection, we first find the second derivative of the function. The second derivative helps us determine the concavity of the function, which is necessary to identify inflection points.

First derivative: f'(x) = 3x^2 - 24x Second derivative: f''(x) = 6x - 24

To find the points of inflection, we set the second derivative equal to zero and solve for x:

6x - 24 = 0 6x = 24 x = 4

Now, we test the concavity of the function around x = 4:

For x < 4, choose x = 3: f''(3) = 6(3) - 24 = 18 - 24 = -6 (negative, so concave down)

For x > 4, choose x = 5: f''(5) = 6(5) - 24 = 30 - 24 = 6 (positive, so concave up)

Since the concavity changes at x = 4, the point (4, f(4)) is an inflection point.

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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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