Finding the Value of b for a Point of Inflection at (2,0)

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In summary, a point of inflection problem involves finding the point at which a curve changes from convex to concave, or vice versa. It is solved by finding the second derivative of the curve and setting it equal to zero. Real-life applications include analyzing supply and demand curves, stress and strain in materials, and the motion of objects. Multiple solutions and special cases can occur in these types of problems.
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coookiemonste
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Homework Statement


If the graph of y=x^3+ax^2+bx-8 has a point of inflection at (2,0), what is the value of b?
the answer is 8.

Homework Equations





The Attempt at a Solution


y'=3x^2+2ax+b
y''=6x+2a
Let y''=0=6x+2a then i plugged in 2 for x
and got -6=a
So y'=3x^2-12x+b...
I don't know where to go from here.
 
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  • #2
You get one more equation from the fact that y = 0 at x = 2.
 
  • #3
i wouldn't of thought of that.
thank you
 

1. What is a point of inflection problem?

A point of inflection problem is a concept in mathematics and physics that involves finding the point at which a curve changes from convex to concave, or vice versa. This point is also known as the inflection point and is where the second derivative of the curve equals zero.

2. How is a point of inflection problem solved?

A point of inflection problem is solved by first finding the second derivative of the curve and setting it equal to zero. This will give the x-coordinate of the inflection point. Then, the first derivative of the curve can be used to find the y-coordinate of the inflection point. The coordinates of the inflection point can then be used to graph the curve and identify the point of inflection.

3. What are some real-life applications of point of inflection problems?

Point of inflection problems have many real-life applications, such as in economics when analyzing the supply and demand curves to determine the equilibrium point. They are also used in engineering to analyze stress and strain in materials, and in physics to study the motion of objects.

4. Can a point of inflection problem have multiple solutions?

Yes, a point of inflection problem can have multiple solutions. In some cases, a curve may have more than one point of inflection, where the second derivative is equal to zero. Additionally, if the second derivative is undefined at a certain point, that point can also be considered an inflection point.

5. Are there any special cases in point of inflection problems?

Yes, there are a few special cases that can occur in point of inflection problems. One is when the second derivative is always equal to zero, meaning there is no inflection point. Another is when the second derivative is always undefined, which can also result in no inflection point. In some cases, the inflection point may also coincide with a critical point, where the first derivative is equal to zero.

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