How to differentiate a equation with three variables

In summary, to find the minimum value of |log_{b}a+log_{a}b| where 'a' and 'b' are positive numbers, you will need to rewrite the equation using the 'change of base formula' and convert log_{b}a into an expression in terms of a logarithm base a. This will give you a single expression in terms of log-base-a, which will help you find the minimum value. However, because of the absolute value sign, there will be two answers for the relationship between a and b.
  • #1
ritwik06
580
0

Homework Statement


Find the minimum value of [tex]|log_{b}a+log_{a}b|[/tex]
where 'a' and 'b' are positive numbers.

First tell me, do I need to differentiate it? If no, then how can this thing be done? I don't know how to differentiate a equation with three variables and that too with modulus involved?

Please help me.
 
Physics news on Phys.org
  • #2


Yes, this problem can be done, but you will need to rewrite it first. Use the 'change of base formula" to convert [tex]log_{b} a[/tex] into an expression in terms of a logarithm base a. (This gives an identity between [tex]log_{a} b[/tex] and [tex]log_{b} a[/tex] that can be useful to know...)

You will now have a single expression, entirely in terms of log-base-a, which will suggest how to find the minimum of the sum.

(BTW, because of the absolute value sign, there will be one answer for the minimum value, but two answers for the relationship between a and b...)
 
Last edited:

FAQ: How to differentiate a equation with three variables

What is the general method for differentiating an equation with three variables?

The general method for differentiating an equation with three variables is to treat each variable as a separate entity and use the basic rules of differentiation such as the power rule, product rule, and chain rule. The goal is to find the rate of change of the equation with respect to one of the variables while holding the other variables constant.

Can I differentiate an equation with three variables using only the power rule?

No, the power rule alone is not sufficient to differentiate an equation with three variables. Differentiating an equation with multiple variables requires the use of other rules such as the product rule and chain rule.

How do I determine which variable to differentiate with respect to in an equation with three variables?

The choice of which variable to differentiate with respect to depends on the context of the problem and what information is being sought. Generally, the variable that is changing or unknown is chosen as the variable to differentiate with respect to.

Are there any special considerations when differentiating an equation with three variables?

Yes, one important consideration is to be aware of the relationships between the variables in the equation. For example, if two or more variables are related by a constant, the constant can be factored out before differentiating. Additionally, it is important to keep track of which variables are being held constant when using the differentiation rules.

Can I use the same differentiation rules for equations with more than three variables?

Yes, the same differentiation rules can be applied to equations with any number of variables. However, as the number of variables increases, the complexity of the equations and the differentiation process also increases. In some cases, it may be more efficient to use other methods such as partial differentiation or implicit differentiation.

Back
Top