How Does the Mean Value Theorem Prove an Inequality Involving Tan^-1?

In summary, the mean value theorem states that for a continuous and differentiable function on a closed interval, there exists a point within that interval where the slope of the tangent line is equal to the average rate of change of the function over that interval. Applying this theorem to the equation tan^-1 x = x, we can show that the absolute value of tan^-1 a is less than the absolute value of a for all values of a not equal to 0. This inequality can then be used to find all solutions of the equation by setting the two sides equal to each other and solving for x.
  • #1
r34racer01
63
0
Use the mean value theorem to show that (abs. value of tan^-1 a) < (abs. value a) for all a not equal to 0. And use this inequality to find all solutions of the equation tan^-1 x = x.

I have no idea how to do this.


 
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  • #2
r34racer01 said:
Use the mean value theorem to show that (abs. value of tan^-1 a) < (abs. value a) for all a not equal to 0. And use this inequality to find all solutions of the equation tan^-1 x = x.

I have no idea how to do this.

Start with what the mean value theorem says, and go from there.
 
  • #3
Mark44 said:
Start with what the mean value theorem says, and go from there.

Well MVT is, if f is cont. on [a,b] and differentiable on (a,b). Then there exists a number c E (a,b) such that: f '(c) = f(b) - f(a)/b-a

But I don't get how to apply that here.
 
  • #4
Well, taking f(x)= tan-1[sup(x) would be a start. What is the derivative of tan-1(x)?
 

What is the Mean Value Theorem Problem?

The Mean Value Theorem Problem is a theorem in calculus that states that if a function is continuous on a closed interval and differentiable on the open interval, then there exists a point within the interval where the slope of the tangent line is equal to the slope of the secant line connecting the endpoints.

What is the significance of the Mean Value Theorem Problem?

The Mean Value Theorem Problem is significant because it is a fundamental theorem in calculus that allows us to prove other important theorems and make predictions about the behavior of functions. It also provides a way to approximate the value of a function at a specific point.

How do you solve a Mean Value Theorem Problem?

To solve a Mean Value Theorem Problem, you first need to check if the given function satisfies the conditions for the theorem. If it does, then you can use the formula f'(c) = (f(b) - f(a))/(b - a) to find the value of c, where a and b are the endpoints of the interval. This value of c will satisfy the theorem and can be used to approximate the value of the function at that point.

What are some real-world applications of the Mean Value Theorem Problem?

The Mean Value Theorem Problem has many real-world applications, including in physics, economics, and engineering. For example, it can be used to calculate the average velocity of an object, determine the rate of change of a stock price, or find the optimal solution to a problem in optimization.

What are the common misconceptions about the Mean Value Theorem Problem?

One common misconception about the Mean Value Theorem Problem is that it only applies to linear functions. In reality, it can be applied to any continuous and differentiable function. Another misconception is that the value of c given by the theorem is always unique, when in fact, there can be multiple values of c that satisfy the theorem within a given interval.

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