Math Problem Statement

Write the limit lim_{Δx → 0} Σ_{i=1}^n 4c_i (7-c_i)^2 Δx_i as a definite integral on the interval [0, 8] where c_i is any point in the i-th subinterval.

Solution

The given question asks us to interpret the limit:

limΔx0i=1n4ci(7ci)2Δxi\lim_{\Delta x \to 0} \sum_{i=1}^n 4c_i (7-c_i)^2 \Delta x_i

as a definite integral on the interval [0,8][0,8], where cic_i is any point in the ii-th subinterval.

Step-by-step Solution:

  1. Identify the form of the sum: The given expression represents a Riemann sum, which approximates the value of a definite integral. The general Riemann sum is of the form: i=1nf(ci)Δxi\sum_{i=1}^n f(c_i) \Delta x_i Here, f(ci)f(c_i) is the function value at some point cic_i within the ii-th subinterval.

  2. Determine the function f(x)f(x): In this case, f(ci)=4ci(7ci)2f(c_i) = 4c_i(7-c_i)^2. So the function we are integrating is: f(x)=4x(7x)2f(x) = 4x(7-x)^2

  3. Set the interval: The interval of integration is given as [0,8][0,8].

  4. Write the definite integral: The limit of the Riemann sum as Δx0\Delta x \to 0 becomes the definite integral: 084x(7x)2dx\int_0^8 4x(7-x)^2 \, dx

Correct Answer:

The correct choice is:

084x(7x)2dx\int_0^8 4x(7-x)^2 \, dx


Would you like more details on how Riemann sums convert into definite integrals or any other aspect of this question?

Related Questions:

  1. What is the meaning of a Riemann sum, and how does it approximate integrals?
  2. How would the integral change if the limits of integration were [1,5][1,5] instead of [0,8][0,8]?
  3. What is the expanded form of the function 4x(7x)24x(7-x)^2 before integration?
  4. Can this integral be solved analytically, and if so, what is its value?
  5. How do different choices of cic_i within the subinterval affect the Riemann sum?

Tip:

When interpreting Riemann sums, always identify the function being evaluated and the interval of integration to write the integral correctly!

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Math Problem Analysis

Mathematical Concepts

Definite Integral
Riemann Sum
Limits

Formulas

Riemann sum: lim_{Δx → 0} Σ f(c_i) Δx_i = ∫_a^b f(x) dx
Function for integration: f(x) = 4x(7-x)^2

Theorems

Fundamental Theorem of Calculus

Suitable Grade Level

Undergraduate Calculus or Advanced High School Calculus