Math Problem Statement

Solution

To find the area of the shaded region between the curves y=x+2y = \sqrt{x + 2} and y=1x+1y = \frac{1}{x + 1} from x=0x = 0 to x=2x = 2, we'll follow these steps:

Step 1: Set up the integral

The area AA of the region between two curves y1(x)y_1(x) and y2(x)y_2(x) from x=ax = a to x=bx = b is given by: A=ab[y1(x)y2(x)]dxA = \int_{a}^{b} \left[ y_1(x) - y_2(x) \right] \, dx Here, y1(x)=x+2y_1(x) = \sqrt{x + 2} (the upper curve) and y2(x)=1x+1y_2(x) = \frac{1}{x + 1} (the lower curve). The bounds are from x=0x = 0 to x=2x = 2.

Step 2: Evaluate the integral

The integral becomes: A=02(x+21x+1)dxA = \int_{0}^{2} \left( \sqrt{x + 2} - \frac{1}{x + 1} \right) \, dx

Let's compute this integral step-by-step.

  1. Integral of x+2\sqrt{x + 2}:

    • Use the substitution u=x+2u = x + 2, so du=dxdu = dx. x+2dx=udu=23u3/2+C=23(x+2)3/2\int \sqrt{x + 2} \, dx = \int \sqrt{u} \, du = \frac{2}{3} u^{3/2} + C = \frac{2}{3} (x + 2)^{3/2}
  2. Integral of 1x+1\frac{1}{x + 1}:

    • This is a standard integral: 1x+1dx=lnx+1+C\int \frac{1}{x + 1} \, dx = \ln|x + 1| + C

So, the area is: A=[23(x+2)3/2lnx+1]02A = \left[ \frac{2}{3} (x + 2)^{3/2} - \ln|x + 1| \right]_{0}^{2}

Step 3: Compute the definite integral

Substitute the bounds x=2x = 2 and x=0x = 0 into the expression:

  1. At x=2x = 2: 23(2+2)3/2ln(2+1)=2343/2ln(3)=238ln(3)=163ln(3)\frac{2}{3} (2 + 2)^{3/2} - \ln(2 + 1) = \frac{2}{3} \cdot 4^{3/2} - \ln(3) = \frac{2}{3} \cdot 8 - \ln(3) = \frac{16}{3} - \ln(3)

  2. At x=0x = 0: 23(0+2)3/2ln(0+1)=2323/2ln(1)=22230=423\frac{2}{3} (0 + 2)^{3/2} - \ln(0 + 1) = \frac{2}{3} \cdot 2^{3/2} - \ln(1) = \frac{2 \cdot 2\sqrt{2}}{3} - 0 = \frac{4\sqrt{2}}{3}

So, the area is: A=(163ln(3))423A = \left( \frac{16}{3} - \ln(3) \right) - \frac{4\sqrt{2}}{3} A=163423ln(3)A = \frac{16}{3} - \frac{4\sqrt{2}}{3} - \ln(3)

Step 4: Simplify the final answer

Combine the terms to get the final area: A=16423ln(3)A = \frac{16 - 4\sqrt{2}}{3} - \ln(3) This expression gives the exact area of the shaded region.

Would you like further details on any part of this process, or help with something else?


Related Questions:

  1. How would the area change if the region was between x=1x = 1 and x=2x = 2 instead of x=0x = 0 to x=2x = 2?
  2. Can you determine where the two curves intersect?
  3. What is the maximum distance between the two curves in the interval x=0x = 0 to x=2x = 2?
  4. How do you determine which curve is the upper one without plotting?
  5. What happens to the area if the upper and lower curves are switched?

Tip:

Always check the intersection points between curves to accurately set the limits of integration when finding areas between curves.

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Math Problem Analysis

Mathematical Concepts

Calculus
Integration
Area Between Curves

Formulas

Integral of a function
Substitution method for integration

Theorems

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Suitable Grade Level

Advanced High School or College Level