How Do I Find the Point of Inflection in a Cubic Graph?

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In summary, the conversation discussed the best approach for finding the point of inflection in a cubic graph. It was suggested to use the definition that the second derivative is 0 and the first derivative changes sign at the inflection point. The participants then clarified that the sign change in the first derivative indicates a change in gradient, while the sign change in the second derivative indicates a change in concavity. The concept of convex and concave curves was also mentioned, with the understanding that a positive second derivative indicates a convex upward curve and a negative second derivative indicates a concave upward curve. It was concluded that at an inflection point, the concavity changes. The conversation then questioned if there is a definition for convex and concave curves.
  • #1
garyljc
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Hey guys ,
I'm currently learning curve sketching
and i was thinking ... what would be the best approach towards finding the point of inflection in a cubic graph . Any suggestions ?
Thanks
 
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  • #2
?? Using the definition- that the second derivative is 0 and the first derivative changes sign there.
 
  • #3
What do you mean by changes sign ?
I do understand that the sign change in the first derivative means the gradient
the second derivative means whether the curve is concave or convex ...
that's all i know about the signs so far..
do you mind elaborating more ?
thanks
 
  • #4
My mistake, I meant that the second derivative changes sign there: is positive on one side of the inflection point and negative on the other. Yes, second derivative positive means the curve is "convex" upward and second derivative negative means the curve is "convex" downward ("concave" upward). At an inflection point the concavity changes.
 
  • #5
i was wondering if there's an definition for convex and concave ... is there ?
 

FAQ: How Do I Find the Point of Inflection in a Cubic Graph?

What is curve sketching?

Curve sketching is a method used in mathematics to create a visual representation of a function or equation. It involves analyzing the features of a curve, such as its intercepts, asymptotes, local extremum, and concavity, to accurately plot the curve on a graph.

Why is curve sketching important?

Curve sketching is important because it allows us to understand and interpret the behavior of a function or equation. It helps us identify key points on a curve and make predictions about its behavior, which is useful in various fields such as economics, physics, and engineering.

What are the key steps in curve sketching?

The key steps in curve sketching include finding the domain and range of the function, determining the intercepts, identifying any asymptotes, analyzing the concavity and points of inflection, and finally plotting the curve on a graph.

How do I find the domain and range of a curve?

The domain of a curve is the set of all values that the independent variable can take. To find the domain, you need to identify any restrictions on the independent variable, such as division by zero or taking the square root of a negative number. The range of a curve is the set of all values that the dependent variable can take. To find the range, you need to consider the behavior of the function as the independent variable approaches positive or negative infinity.

What are asymptotes and how do I identify them?

Asymptotes are lines that a curve approaches but never touches. They can be vertical, horizontal, or slanted. To identify asymptotes, you need to analyze the behavior of the function as the independent variable approaches certain values. For vertical asymptotes, the function will approach either positive or negative infinity. For horizontal asymptotes, the function will approach a constant value. For slanted asymptotes, the function will approach a linear function.

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