Graphing Y=1/x + 1/(x+1): Problem with Curve Sketching Methods

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SUMMARY

The discussion focuses on graphing the equation y = 1/x + 1/(x+1) and the challenges encountered while applying curve sketching methods. The second derivative, y'' = [2(x+1)^3 + 2x^3]/x^3(x+1)^3, is confirmed to be correct, but the user struggles with finding critical numbers from the numerator. The behavior of the graph is analyzed, noting that 1/(x+1) dominates in the region where x > 0, while 1/x is more significant as x approaches zero from the right. Various methods for solving the equation x^3 + (x+1)^3 = 0 are discussed, including factoring and using the sum of cubes formula.

PREREQUISITES
  • Understanding of calculus concepts, particularly derivatives and critical points.
  • Familiarity with curve sketching techniques and asymptotic behavior.
  • Knowledge of algebraic factoring methods, including the sum of cubes.
  • Experience with graphing rational functions and their properties.
NEXT STEPS
  • Study the application of the second derivative test for identifying concavity and inflection points.
  • Learn about the behavior of rational functions near their asymptotes.
  • Explore advanced factoring techniques, specifically the sum of cubes and its applications.
  • Investigate graphing software tools that can visualize complex functions and their derivatives.
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Mathematics students, educators, and anyone involved in calculus or graphing functions will benefit from this discussion, particularly those focusing on curve sketching and rational function analysis.

nameVoid
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in try to use curve sketching methods to graph this equation I've come across a problem in

y''=[2(x+1)^3+2x^3]/x^3(x+1)^3

I have verified this equation for y'' is correct but solving the numerator for critical numbers by hand ?
 
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How accurate does the graph need to be?

I mean you know how the graph 1/x looks like (I hope you do), 1/(x+1) is similar but with an asymptote in x=-1, the graph should be a superposition of these graphs, so if x+1>0, the graph of 1/(x+1) will tend more rapidly to zero than 1/x so it's dominant in the region of x>0, so the tendency of y to zero should be similar to 1/(x+1) from -1 to zero, and for 0<x<<1 the 1/x is dominant.
 
There several ways to solve x^3+(x+1)^3=0 by hand. i) Multiply it out and factor it. ii) There's a formula to factor the sum of two cubes. Or iii) write it as -x^3=(x+1)^3 and take the cube root. You'll lose the complex roots if you do it that way, but you don't need them for this problem anyway.
 

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