Math Problem Statement

Using the definition of Riemann integral, evaluate several integrals and analyze the integrability of various functions over specified intervals. Apply the Mean Value Theorem for integrals to certain functions and verify it for given integrals. Differentiate integral functions and perform proofs related to integral calculus.

Solution

Let's address these questions one by one with explanations and solutions where applicable.

Question 1: Using the definition of Riemann integral, evaluate the following:

The question involves evaluating integrals using the definition of the Riemann integral for the given functions:

  1. 0abxdx\int_0^a b^x dx
  2. 0bexdx\int_0^b e^x dx
  3. 0π/2sin2xdx\int_0^{\pi/2} \sin^2 x dx
  4. 0adxx\int_0^a \frac{dx}{x}
  5. 0a(1+x)dx\int_0^a (1 + x) dx

These integrals can be computed by standard techniques in calculus, such as substitution or known integral formulas.

Question 2: Determine which of the following functions are integrable over the indicated intervals.

This question involves checking the integrability of functions defined piecewise, where many of them involve rational and irrational domains. A function defined on an interval [a,b][a, b] is integrable if it is bounded and has only a finite number of discontinuities in that interval.

Approach:

  1. For each function, analyze whether it is bounded on the given interval.
  2. Check if it has a countable number of discontinuities (as functions with uncountable discontinuities are generally not Riemann integrable).

Question 3: Derive the Mean Value Theorem for integrals by applying Lagrange's Mean Value Theorem to the function F(x)=axf(t)dtF(x) = \int_a^x f(t) dt.

To apply the Mean Value Theorem, rewrite F(x)F(x) in terms of the Mean Value Theorem for integrals:

  1. State the conditions for ff under which the Mean Value Theorem can be applied (continuity on [a,b][a, b]).
  2. Conclude that there exists a c(a,b)c \in (a, b) such that F(b)F(a)=f(c)(ba)F(b) - F(a) = f(c)(b - a).

Question 4: Verify the Mean Value Theorem for the following definite integrals.

  1. 0πsinxdx\int_0^{\pi} \sin x dx
  2. 01exdx\int_0^1 e^x dx
  3. 04x2dx\int_0^4 x^2 dx

For each integral:

  1. Calculate the definite integral value.
  2. Identify the point cc that satisfies the theorem.

Question 5: Find F(x)F'(x) for the given integral functions F(x)F(x).

  1. Use the Fundamental Theorem of Calculus to differentiate each given function F(x)F(x) if it’s expressed as an integral with an upper bound depending on xx.

Question 6: Prove that dydx=y\frac{dy}{dx} = y when xx and yy are related by x=0ydt1+t2x = \int_0^y \frac{dt}{\sqrt{1 + t^2}}.

This problem requires differentiating the integral relationship given between xx and yy using implicit differentiation and the chain rule.

Question 7: Prove that abf(x)g(x)dx=f(c)abg(x)dx\int_a^b f(x)g(x) dx = f(c) \int_a^b g(x) dx for some c[a,b]c \in [a, b], given that ff and gg are continuous and g(x)g(x) does not change sign on [a,b][a, b].

For this proof:

  1. Use the Mean Value Theorem for integrals, given the continuity of ff and gg and the constant sign of g(x)g(x) over the interval.

Would you like detailed solutions to any specific questions from this list?

Related Questions

  1. How can we determine if a function is integrable over a certain interval?
  2. What conditions are necessary to apply the Mean Value Theorem in integral calculus?
  3. How do we handle piecewise functions when determining integrability?
  4. What is the significance of continuity in proving the Mean Value Theorem?
  5. How does the Fundamental Theorem of Calculus relate to finding derivatives of integral functions?

Tip

When dealing with Riemann integrals of piecewise functions, always check the count and type of discontinuities, as this affects their integrability over the interval.

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Math Problem Analysis

Mathematical Concepts

Riemann Integration
Integrability
Mean Value Theorem for Integrals
Differentiation of Integral Functions
Implicit Differentiation

Formulas

Fundamental Theorem of Calculus
Mean Value Theorem for Integrals
Definition of Riemann integral

Theorems

Mean Value Theorem
Fundamental Theorem of Calculus

Suitable Grade Level

Undergraduate Calculus