Solving 2 Questions on Continuity in R^2

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SUMMARY

This discussion addresses two mathematical questions regarding continuity in R². The first question involves proving the existence of a continuous function g on R¹ that matches a given continuous function f on a closed subset E of R¹. The second question examines the boundedness of two functions defined on R²: f(x,y) = xy²/(x²+y⁴) and g(x,y) = xy²/(x²+y⁶), demonstrating that f is bounded while g is unbounded near (0,0). Key techniques include evaluating limits and using graphing calculators for visual analysis.

PREREQUISITES
  • Understanding of real continuous functions
  • Knowledge of limits and boundedness in multivariable calculus
  • Familiarity with closed subsets in R¹
  • Experience with graphing calculators for function analysis
NEXT STEPS
  • Study the properties of continuous functions on closed subsets in R¹
  • Learn about bounded and unbounded functions in multivariable calculus
  • Explore limit evaluation techniques for functions of two variables
  • Practice using graphing calculators to analyze function behavior near critical points
USEFUL FOR

Students and educators in mathematics, particularly those studying calculus and real analysis, as well as anyone interested in the properties of continuous functions and their applications in R².

Ka Yan
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Two questions need helps

I got two questions below need helps:

1. Let f be a real continuous function defined on a closed subset E of R[tex]^1[/tex], then how can I prove the existence of some corressponding real continuous functions g on R[tex]^1[/tex], such that g(x)=f(x) for all x[tex]\in[/tex]E ?

2. Let f and g two functions defined on R[tex]^2[/tex] by: f(0,0)=g(0,0)=0, f(x,y)=xy[tex]^2[/tex]/(x[tex]^2[/tex]+y[tex]^4[/tex]), and g(x,y)=xy[tex]^2[/tex]/(x[tex]^2[/tex]+y[tex]^6[/tex]), if (x,y)[tex]\neq[/tex](0,0). Then how can I prove that: (1) f is bounded on R[tex]^2[/tex], and (2) g is unbounded in every neighborbood of (0,0) ?

Thks!
 
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You're supposed to show some sort of attempt at solving the problem in order to get here. ;)

The question seems a little unclear to me-basically #1 is just asking you to prove that two equations are equal to each other. On #2, You can prove that f is bounded by setting the equations equal to zero and solving for when x=0. Or you can use your graphing calculator.

I could be wrong, (just a high school student), but from the limited information here, that's about all I can come up with.
 

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