Understanding Mean Value Theorem: Solving Homework Problems

In summary, the first three equations are from the textbook, and the last two equations are from notes that the student took. The fourth equation is incorrect, and the fifth equation is true.
  • #1
Slimsta
190
0

Homework Statement


http://img14.imageshack.us/img14/6132/proiqc.jpg


Homework Equations





The Attempt at a Solution


the first 3 are from the textbook so they must be right.. the last 2 I am pretty sure i got right too..
because the 4th one, if f'(x)=0 then f(x)= c .. so its false.
im not too sure about the 5th one but I am 90% sure it should true.
 
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  • #2
(1) is Rolle's Theorem (Edit: this is incorrect - see the following posts)
(2) is the Mean Value Theorem, which is a generalization of Rolle's Theorem
I did not know (3) but that is interesting
(4) is correct, f(x) can be a constant function not equal to 0.
(5) is correct - take a(x) = f(x) - g(x). It's derivative is 0, so a(x) is constant (you can prove this using MVT).
 
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  • #3
VeeEight said:
(1) is Rolle's Theorem
(2) is the Mean Value Theorem, which is a generalization of Rolle's Theorem
I did not know (3) but that is interesting
(4) is correct, f(x) can be a constant function not equal to 0.
(5) is correct - take a(x) = f(x) - g(x). It's derivative is 0, so a(x) is constant (you can prove this using MVT).

i know that 1 and 2 are Rolle's Theorem and Mean Value Theorem, and its written exactly like in my textbook.. i can't find the mistake.

https://www.physicsforums.com/library.php?do=view_item&itemid=231 its even stated here..

so what is wrong?
 
  • #4
Oh sorry, I missed that
(1) states that f is defined on [a,b] but it is not necessarily continuous there. It is continuous on (a,b) (since it is differentiable there) but not necessarily at a or b.
 
  • #5
VeeEight said:
Oh sorry, I missed that
(1) states that f is defined on [a,b] but it is not necessarily continuous there. It is continuous on (a,b) (since it is differentiable there) but not necessarily at a or b.

thats a tricky question.. weird.
thanks a lot for your help man!
 
  • #6
No problem, can't believe I missed that
In my experience, the physical science courses are where they try to 'trick' you like that, I've never had any questions like that when I was a math undergrad. I guess now you've learned that you have to pay attention to every little detail when writing tests in this class (which is probably a good idea, regardless). Cheers.
 

FAQ: Understanding Mean Value Theorem: Solving Homework Problems

1. What is the Mean Value Theorem?

The Mean Value Theorem is a fundamental theorem in calculus that states that for any continuous function on a closed interval, there exists at least one point in the interval where the instantaneous rate of change (derivative) is equal to the average rate of change. In other words, it guarantees the existence of a tangent line that is parallel to the secant line connecting the endpoints of the interval.

2. How is the Mean Value Theorem used in calculus?

The Mean Value Theorem is used to prove other important theorems and formulas in calculus, such as the First and Second Derivative Tests for finding extrema, the Fundamental Theorem of Calculus for evaluating definite integrals, and the Intermediate Value Theorem for proving the existence of roots of equations.

3. What are the conditions for the Mean Value Theorem to hold?

The Mean Value Theorem requires that the function is continuous on a closed interval and differentiable on the open interval. This means that there cannot be any breaks or holes in the graph of the function, and the function must have a well-defined derivative at every point in the interval.

4. Can the Mean Value Theorem be applied to all functions?

No, the Mean Value Theorem is only applicable to continuous functions on a closed interval. If a function is discontinuous or undefined at certain points, it cannot satisfy the conditions for the Mean Value Theorem to hold.

5. How is the Mean Value Theorem related to Rolle's Theorem?

Rolle's Theorem is a special case of the Mean Value Theorem where the average and instantaneous rates of change are equal at the endpoints, resulting in a derivative of zero at some point in the interval. In other words, the Mean Value Theorem is a generalization of Rolle's Theorem, and both are used to prove important results in calculus.

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