Math Problem Statement

Find the left and right hand limit

Find the left and right hand limit of the integral of y = e^x over the interval [1,3]

Solution

To find the left-hand and right-hand Riemann sums for the integral of y=exy = e^x over the interval [1,3][1, 3], you need to approximate the area under the curve by dividing the interval into nn subintervals and then applying the Riemann sum formulas.

  1. Partition the interval: Divide [1,3][1, 3] into nn subintervals of equal width, where each subinterval width Δx\Delta x is given by: Δx=31n=2n\Delta x = \frac{3 - 1}{n} = \frac{2}{n}

  2. Left Riemann Sum (Lower Sum): For the left Riemann sum, evaluate y=exy = e^x at the left endpoint of each subinterval. If we let xi=1+(i1)Δxx_i = 1 + (i-1)\Delta x, the left Riemann sum LnL_n is: Ln=i=1nexi1Δx=i=1ne1+(i1)2n2nL_n = \sum_{i=1}^{n} e^{x_{i-1}} \cdot \Delta x = \sum_{i=1}^{n} e^{1 + (i-1)\frac{2}{n}} \cdot \frac{2}{n}

  3. Right Riemann Sum (Upper Sum): For the right Riemann sum, evaluate y=exy = e^x at the right endpoint of each subinterval. If we let xi=1+iΔxx_i = 1 + i\Delta x, the right Riemann sum RnR_n is: Rn=i=1nexiΔx=i=1ne1+i2n2nR_n = \sum_{i=1}^{n} e^{x_i} \cdot \Delta x = \sum_{i=1}^{n} e^{1 + i\frac{2}{n}} \cdot \frac{2}{n}

  4. Taking the Limit: To find the exact value of the integral as nn \to \infty, compute the integral directly: 13exdx=[ex]13=e3e1\int_{1}^{3} e^x \, dx = \left[ e^x \right]_1^3 = e^3 - e^1

Would you like further details on these calculations, or do you have any specific questions?

Here are some related questions to deepen your understanding:

  1. How does the Riemann sum change as nn increases?
  2. What is the significance of the difference between the left-hand and right-hand Riemann sums?
  3. How would you approximate this integral using a midpoint Riemann sum?
  4. What happens if you approximate this integral using trapezoidal sums instead?
  5. Why does taking the limit as nn \to \infty provide the exact area?

Tip: Increasing the number of subintervals nn improves the accuracy of the Riemann sum approximation, bringing it closer to the exact integral value.

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Math Problem Analysis

Mathematical Concepts

Calculus
Integral Calculus
Riemann Sums

Formulas

Left Riemann Sum: L_n = \sum_{i=1}^{n} e^{1 + (i-1)\frac{2}{n}} \cdot \frac{2}{n}
Right Riemann Sum: R_n = \sum_{i=1}^{n} e^{1 + i\frac{2}{n}} \cdot \frac{2}{n}
Integral Calculation: \int_{1}^{3} e^x dx = e^3 - e^1

Theorems

Fundamental Theorem of Calculus

Suitable Grade Level

College Level Calculus