Math Problem Statement

Use the figures to calculate the left and right Riemann sums for f on the given interval and the given value of n. ​f(x)equalsxplus2 on ​[2​,7​]; nequals5

Use the figures to calculate the left and right Riemann sums for f on the given interval and the given value of n. f(x) = x + 2 on [2, 7]; n = 5

Solution

To calculate the left and right Riemann sums for f(x)=x+2f(x) = x + 2 over the interval [2,7][2, 7] with n=5n = 5, we will proceed as follows:

  1. Determine the width of each subinterval (Δx\Delta x): Δx=725=1\Delta x = \frac{7 - 2}{5} = 1

  2. Left Riemann Sum: For the left Riemann sum, we use the function values at the left endpoints of each subinterval. The left endpoints are x=2,3,4,5,x = 2, 3, 4, 5, and 66.

    • f(2)=2+2=4f(2) = 2 + 2 = 4
    • f(3)=3+2=5f(3) = 3 + 2 = 5
    • f(4)=4+2=6f(4) = 4 + 2 = 6
    • f(5)=5+2=7f(5) = 5 + 2 = 7
    • f(6)=6+2=8f(6) = 6 + 2 = 8

    The left Riemann sum is then: L5=Δx(f(2)+f(3)+f(4)+f(5)+f(6))L_5 = \Delta x \cdot (f(2) + f(3) + f(4) + f(5) + f(6)) L5=1(4+5+6+7+8)=130=30L_5 = 1 \cdot (4 + 5 + 6 + 7 + 8) = 1 \cdot 30 = 30

  3. Right Riemann Sum: For the right Riemann sum, we use the function values at the right endpoints of each subinterval. The right endpoints are x=3,4,5,6,x = 3, 4, 5, 6, and 77.

    • f(3)=3+2=5f(3) = 3 + 2 = 5
    • f(4)=4+2=6f(4) = 4 + 2 = 6
    • f(5)=5+2=7f(5) = 5 + 2 = 7
    • f(6)=6+2=8f(6) = 6 + 2 = 8
    • f(7)=7+2=9f(7) = 7 + 2 = 9

    The right Riemann sum is then: R5=Δx(f(3)+f(4)+f(5)+f(6)+f(7))R_5 = \Delta x \cdot (f(3) + f(4) + f(5) + f(6) + f(7)) R5=1(5+6+7+8+9)=135=35R_5 = 1 \cdot (5 + 6 + 7 + 8 + 9) = 1 \cdot 35 = 35

Summary:

  • Left Riemann Sum (L5L_5): 30
  • Right Riemann Sum (R5R_5): 35

Would you like more details on this process or have any other questions?

Here are some related questions you might explore:

  1. What is the average of the left and right Riemann sums, and how does it relate to the midpoint Riemann sum?
  2. How would the Riemann sums change if nn were increased, say to n=10n = 10?
  3. Can we calculate the exact area under f(x)=x+2f(x) = x + 2 from x=2x = 2 to x=7x = 7 using integration?
  4. How would we set up a trapezoidal sum for this function on the interval [2,7][2, 7] with n=5n = 5?
  5. How do left and right Riemann sums compare in accuracy for different types of functions?

Tip: Increasing nn generally improves the accuracy of Riemann sums by providing a closer approximation to the actual area.

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Math Problem Analysis

Mathematical Concepts

Calculus
Riemann Sums
Integration Approximation

Formulas

Δx = (b - a) / n
Left Riemann Sum = Δx * Σ f(x_i) for i = left endpoints
Right Riemann Sum = Δx * Σ f(x_i) for i = right endpoints

Theorems

Riemann Sum Approximation

Suitable Grade Level

Grades 11-12 or College Calculus