Math Problem Statement

The shaded region shown below is bounded by the functions f(x) = -x^2 + 4 and g(x) = -0.75x + 3, the y-axis, and the line x = 2. Find the area of the shaded region using a calculator. Round your answer to the nearest thousandth.

Solution

The given problem asks for the area of the shaded region bounded by the functions f(x)=x2+4f(x) = -x^2 + 4, g(x)=0.75x+3g(x) = -0.75x + 3, the yy-axis, and the vertical line x=2x = 2. I'll solve this step by step by calculating the definite integral of the difference between the two functions over the given interval.


Step 1: Set up the limits of integration

The area is between x=0x = 0 (the yy-axis) and x=2x = 2 (the given vertical line). The area between two curves is found by integrating the difference of the top function and the bottom function.

  • The top function is f(x)=x2+4f(x) = -x^2 + 4.
  • The bottom function is g(x)=0.75x+3g(x) = -0.75x + 3.

Step 2: Write the area formula

The formula for the area is:

Area=02[(x2+4)(0.75x+3)]dx\text{Area} = \int_0^2 \left[(-x^2 + 4) - (-0.75x + 3)\right] \, dx

Simplifying the expression inside the integral:

02(x2+4+0.75x3)dx\int_0^2 \left(-x^2 + 4 + 0.75x - 3\right) \, dx

=02(x2+0.75x+1)dx= \int_0^2 \left(-x^2 + 0.75x + 1\right) \, dx


Step 3: Calculate the integral

We'll integrate each term separately:

02x2dx+020.75xdx+021dx\int_0^2 -x^2 \, dx + \int_0^2 0.75x \, dx + \int_0^2 1 \, dx

  1. Integral of x2-x^2: 02x2dx=[x33]02=83\int_0^2 -x^2 \, dx = \left[-\frac{x^3}{3}\right]_0^2 = -\frac{8}{3}

  2. Integral of 0.75x0.75x: 020.75xdx=[0.75×x22]02=0.75×2=1.5\int_0^2 0.75x \, dx = \left[0.75 \times \frac{x^2}{2}\right]_0^2 = 0.75 \times 2 = 1.5

  3. Integral of 11: 021dx=[x]02=2\int_0^2 1 \, dx = \left[x\right]_0^2 = 2


Step 4: Add the results

83+1.5+2=83+3.5×33=8+10.53=2.53-\frac{8}{3} + 1.5 + 2 = \frac{-8}{3} + \frac{3.5 \times 3}{3} = \frac{-8 + 10.5}{3} = \frac{2.5}{3}

Let me double-check calculations.

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Math Problem Analysis

Mathematical Concepts

Definite Integration
Area between Curves

Formulas

Area between curves formula: ∫[a to b] (f(x) - g(x)) dx

Theorems

Fundamental Theorem of Calculus

Suitable Grade Level

Grades 11-12