Concavity Test: Finding the Concavity of y=2+3x-x^3 Using Derivatives

  • Thread starter Thread starter phillyolly
  • Start date Start date
Click For Summary
SUMMARY

The discussion focuses on determining the concavity of the function y=2+3x-x³ using the Second Derivative Test. The first derivative is calculated as y'=3-3x², and the second derivative is y''=-6x. The function is concave down where y''<0 and concave up where y''>0. The inflection point occurs when y''=0, specifically at x=0, indicating a change in concavity around this point.

PREREQUISITES
  • Understanding of derivatives, specifically first and second derivatives.
  • Familiarity with the concept of concavity in calculus.
  • Knowledge of inflection points and their significance in graphing functions.
  • Ability to analyze intervals using inequalities.
NEXT STEPS
  • Study the implications of the Second Derivative Test in greater detail.
  • Explore how to graph functions based on concavity and inflection points.
  • Learn about higher-order derivatives and their applications in concavity analysis.
  • Investigate the relationship between concavity and the behavior of polynomial functions.
USEFUL FOR

Students studying calculus, particularly those focusing on derivatives and concavity analysis, as well as educators seeking to explain these concepts effectively.

phillyolly
Messages
157
Reaction score
0

Homework Statement



y=2+3x-x3

The Attempt at a Solution



y'=3-3x2
y''=-6x

Please help me out finding the concavity of the function by using the Concavity Test or the Second derivative test.
 
Physics news on Phys.org
y is concave down if y''< 0 and concave up if y''> 0. For what values of x is y'' negative? positive? The point at which y''= 0 is called an inflection. You should end up having y(x) as concave down for roughly half of its domain and concave up for the other half. You should be able to do the rest. And make sure to check whether the ends of the two sets of points are open or closed, i.e., do we need [a,b] or (a,b] or [a,b) or (a,b)?
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 6 ·
Replies
6
Views
2K
Replies
5
Views
1K
  • · Replies 12 ·
Replies
12
Views
2K
Replies
7
Views
2K
  • · Replies 24 ·
Replies
24
Views
3K
  • · Replies 25 ·
Replies
25
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 11 ·
Replies
11
Views
2K