Irrational denominator limit derivative

In summary, the conversation is about finding the derivative of the function f(x) = \frac{1}{\sqrt{x + 2}} and the methods used to solve it, including rationalizing the denominator and using the chain rule. The possibility of using the basic definition of the derivative for practice is also mentioned.
  • #1
Orion1
973
3


Can anyone provide some information for this formula?

I tried rationalizing the denominator and cross multiplication and combining terms, and also multiplying by the conjugate of the demoninator, what am I doing wrong?

[tex]f(x) = \frac{1}{\sqrt{x + 2}} \; \; \; \text{find} \; f'(a)[/tex]

[tex]f'(a) = \lim_{h \rightarrow 0} (\frac{1}{\sqrt{(a + h) + 2}} - \frac{1}{\sqrt{a + 2}}) \frac{1}{h}[/tex]

 
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  • #2
Ok. don't write it any more complicated than it already is. It's actaully not very hard...

write it as [tex]f(x)=(x+2)^{-1/2}[/tex] and apply the chain rule. Or power Rule...I don't know them by name. Especially since x has no coefficient it's very "clean".

to answer the "what I'm doing wrong" part...you don't want to apply the [tex]\frac{f(x+h)-f(x)} {h}[/tex] unless absolutely everything else fails. I mean once you're past chapter 2 calculus AB it becomes unused until maybe way later which I'd not know.
 
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  • #3
Robokapp, you should consider the possibility that Orion1 is required to use the basic definition of the derivative for practice. Of course, if that's the case, then this is school work so I am moving this thread to the homework section!

Orion1, first subtract the two fractions, getting
[tex]\frac{\sqrt{x+2}- \sqrt{x+h+2}}{\sqrt{x+2}\sqrt{x+h+2}}[/tex]
then try "rationalizing the numerator": multiply both numerator and denominator by
[tex]\sqrt{x+2}+ \sqrt{x+h+2}[/tex]
 

What is an irrational denominator limit derivative?

An irrational denominator limit derivative is a mathematical concept that involves taking the derivative of a function when the denominator contains an irrational number, such as pi or the square root of a non-perfect square.

Why is an irrational denominator limit derivative important?

An irrational denominator limit derivative is important because it allows us to find the instantaneous rate of change of a function at a specific point, even when the denominator contains an irrational number. This is useful in many real-world applications, such as engineering and physics.

How do you solve for an irrational denominator limit derivative?

To solve for an irrational denominator limit derivative, we use the quotient rule, which states that the derivative of a fraction is equal to the bottom function times the derivative of the top function minus the top function times the derivative of the bottom function, all divided by the bottom function squared. This allows us to find the derivative even when the denominator contains an irrational number.

Can an irrational denominator limit derivative ever be undefined?

Yes, an irrational denominator limit derivative can be undefined. This typically occurs when the bottom function is equal to 0, which would make the entire expression undefined. It is important to always check for these cases when solving for an irrational denominator limit derivative.

How can I practice and improve my understanding of irrational denominator limit derivatives?

The best way to practice and improve your understanding of irrational denominator limit derivatives is to work through practice problems and exercises. You can also seek out additional resources, such as textbooks or online tutorials, to further your understanding. Additionally, seeking help from a tutor or attending a study group can also be beneficial.

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