Derivative of f(x)=1/x at x=2 using the Limit Definition

  • Thread starter eddieberto
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In summary, to find the derivative of a function at a given point, we can use the definition f(a)=limit...f(a+h)-f(a)...h->0...__________......h and substitute the function and point into the limit expression. Simplify the expression and cancel out any common terms to find the derivative. In this specific example, the function f(x)=1/x evaluated at a=2 results in a derivative of -1/4.
  • #1
eddieberto
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it tells me to use the definition

f(a)=limit...f(a+h)-f(a)
...h->0...__________
......h


to find the derivative of the given function at the indicated poin.
f(x)=1/x, a=2



I don't kno what to do
 
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  • #2


its hard to read, try teh tex belwo (click on it)
[tex] lim_{h \rightarrow 0}\frac{f(a+h) - f(a)}{h} [/tex]

try subsituting into the limit for your function evaulated at x = a, and x = a+h
 
  • #3


this is how far i got and then i got lost

[tex]
lim_{h \rightarrow 0}\frac{a-(a+h)}{h(a+h)(a)}
[/tex]
and the answer is supos to be -1/4

im lost
 
  • #4


you're not that far off, simplify the top line, then see what you cancel
 
  • #5


thanks i got it
 

1. What is the definition of f(a)=limit?

The definition of f(a)=limit is a mathematical concept that represents the value that a function approaches as its input, a, approaches a specific value. It is written as lim f(a) = L, where L is the limit of the function at the value a.

2. How is the limit of a function calculated?

The limit of a function can be calculated by evaluating the function at values of a that are very close to the given value and observing the trend of the function's output. Alternatively, you can use algebraic techniques such as factoring and canceling to simplify the function and determine the limit.

3. What is the purpose of finding the limit of a function?

The main purpose of finding the limit of a function is to understand the behavior of the function near a specific value. This can help in determining the continuity, differentiability, and overall behavior of the function at that point. It is also useful in solving real-world problems involving rates of change.

4. Can a function have a limit at a point where it is not defined?

Yes, a function can have a limit at a point where it is not defined. This is because the limit only considers the behavior of the function near a specific value, not necessarily at that value. As long as the function approaches a specific value as its input gets closer to the given value, the limit exists.

5. How can the definition of f(a)=limit be applied in real-world situations?

The definition of f(a)=limit can be applied in various real-world situations, such as in physics to determine the velocity and acceleration of an object, in economics to analyze the growth rate of a company, and in biology to understand the rate of change of a population. It can also be used in engineering and finance to model and predict the behavior of systems and investments.

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