Limits of Multivariable equations

This may help you achieve a form that is easier to work with. In summary, the conversation discusses finding the limit of a function as x and y approach 0, and the attempts made to solve it using l'hopital's rule. The speaker suggests changing the expression to \left(2x^2\right)^{-1} in order to make the problem more manageable.
  • #1
cappygal
9
0
I need to find the limit as x,y->0 of (x^2+y^2)(ln(x^2+2y^2)) anylitically.
since the limit of this is 0(-infinity) which is indeterminant .. I tried to approach it along the line y=x which gives:
lim(x->0) of [2x^2*ln(3x^2)]. Again, that gives 0(-infinity). Now, I haven't done calculus in 6 months .. I know I need to get it to a quotient indeterminant form in order to be able to use l'hopital's rule ..
I tried:
lim (x->0) of [2x^2/(ln(3x^2)^-1] but that gives 0/(1/(-infinity) .. that's indeterminant, so I can take the derivitive, and get:
lim (x->0) of [4x/(-1(ln(3x^2)^-2)(1/(3x^2))(6x)] :yuck:
which is
lim (x->0) of [(4x*3x^2)/(-6xln(3x^2)^-2)] which is 0/0 ..
I don't think this is getting me anywhere. Any ideas on how to make this work? :yuck: Thanks!
 
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  • #2
Instead of changing [itex]\ln\left(3x^2\right)[/itex] to [itex]\left(\ln\left(3x^2\right)\right)^{-1}[/itex], try changing [itex]2x^2[/itex] to [itex]\left(2x^2\right)^{-1}[/itex].
 

1. What is a multivariable equation?

A multivariable equation is an algebraic expression that contains multiple variables. These equations can have two or more variables and involve operations such as addition, subtraction, multiplication, and division.

2. What are the limits of multivariable equations?

The limits of multivariable equations refer to the boundaries or constraints within which the equation holds true. These limits can be defined by the values assigned to the variables or by the conditions stated in the equation.

3. How do you determine the limits of a multivariable equation?

The limits of a multivariable equation can be determined by analyzing the behavior of the equation as the values of the variables approach certain values or as the conditions of the equation change. This can be done through graphing, substitution, or other mathematical methods.

4. What are some real-world applications of multivariable equations?

Multivariable equations have many real-world applications, such as in economics, physics, engineering, and statistics. They can be used to model complex systems and relationships between multiple variables, allowing for more accurate predictions and analysis.

5. What are some challenges in dealing with multivariable equations?

Some challenges in dealing with multivariable equations include the complexity of the equations, the difficulty in visualizing and interpreting them, and the potential for errors in calculations. Multivariable equations also require a thorough understanding of algebra and mathematical concepts.

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