Math Problem Statement

Evaluate definite integrals using geometric formulas based on a graph consisting of line segments. Integrals given: (a) \( \int_0^1 -2f(x) \, dx \), (b) \( \int_3^4 8f(x) \, dx \), (c) \( \int_0^7 6f(x) \, dx \), (d) \( \int_5^{11} -3f(x) \, dx \), (e) \( \int_0^{11} 2f(x) \, dx \), (f) \( \int_4^{10} 2f(x) \, dx \).

Solution

From the uploaded image, you are tasked with evaluating definite integrals based on a graph consisting of line segments. Each definite integral can be evaluated using geometric formulas by finding the area under the graph of f(x)f(x) multiplied by the given scalar for each case. Let's solve each part step by step:

Analysis of Graph:

The graph is segmented into linear pieces with defined vertices. Key points are marked as:

  • (0,0)(0, 0)
  • (3,2)(3, 2)
  • (4,2)(4, 2)
  • (8,2)(8, -2)
  • (11,1)(11, 1)

Geometric Formulas:

For these problems, calculate the areas of triangles and rectangles formed by the graph and consider the multiplier (e.g., 2f(x)2f(x), 8f(x)8f(x)).


(a) 012f(x)dx\int_0^1 -2f(x) \, dx

  • f(x)=0f(x) = 0 from x=0x = 0 to x=1x = 1. Since f(x)=0f(x) = 0, the integral evaluates to 0.

(b) 348f(x)dx\int_3^4 8f(x) \, dx

  • From x=3x = 3 to x=4x = 4, f(x)=2f(x) = 2.
  • The integral is the area of a rectangle with height 22 and width 11, multiplied by 8: 348f(x)dx=8(12)=16\int_3^4 8f(x) \, dx = 8 \cdot (1 \cdot 2) = 16

(c) 076f(x)dx\int_0^7 6f(x) \, dx

  • Break the interval into segments:
    • x=0x = 0 to 33: Triangle with base 33 and height 22: Area=12(3)(2)=3\text{Area} = \frac{1}{2}(3)(2) = 3
    • x=3x = 3 to 44: Rectangle with width 11 and height 22: Area=2\text{Area} = 2
    • x=4x = 4 to 77: Triangle with base 33 and height 2-2: Area=12(3)(2)=3\text{Area} = \frac{1}{2}(3)(-2) = -3
  • Total weighted area: 6(3+23)=62=126 \cdot (3 + 2 - 3) = 6 \cdot 2 = 12

(d) 5113f(x)dx\int_5^{11} -3f(x) \, dx

  • Break into segments:
    • x=5x = 5 to 88: Triangle with base 33 and height 2-2: Area=12(3)(2)=3\text{Area} = \frac{1}{2}(3)(-2) = -3
    • x=8x = 8 to 1111: Triangle with base 33 and height 11: Area=12(3)(1)=1.5\text{Area} = \frac{1}{2}(3)(1) = 1.5
  • Total weighted area: 3(3+1.5)=31.5=4.5-3 \cdot (-3 + 1.5) = -3 \cdot -1.5 = 4.5

(e) 0112f(x)dx\int_0^{11} 2f(x) \, dx

  • Add all areas:
    • x=0x = 0 to 33: 33
    • x=3x = 3 to 44: 22
    • x=4x = 4 to 88: 3-3
    • x=8x = 8 to 1111: 1.51.5
  • Total area: 2(3+23+1.5)=23.5=72 \cdot (3 + 2 - 3 + 1.5) = 2 \cdot 3.5 = 7

(f) 4102f(x)dx\int_4^{10} 2f(x) \, dx

  • Add areas:
    • x=4x = 4 to 88: 3-3
    • x=8x = 8 to 1010: Part of the triangle x=8x = 8 to x=11x = 11:
      • Height 11, base 33, consider 23\frac{2}{3} of the area: Area=12(1)(2)=1\text{Area} = \frac{1}{2}(1)(2) = 1
  • Total area: 2(3+1)=22=42 \cdot (-3 + 1) = 2 \cdot -2 = -4

Final Answers:

(a) 00
(b) 1616
(c) 1212
(d) 4.54.5
(e) 77
(f) 4-4

Would you like step-by-step elaboration on any specific part or further explanation?


Expanding Thoughts:

  1. How does the scaling constant affect the result of an integral?
  2. Why is the area below the x-axis considered negative?
  3. What is the importance of geometric interpretation in definite integrals?
  4. How can such problems apply to physics or economics?
  5. What happens when the limits of integration are reversed?

Tip: Always sketch graphs when solving definite integrals, especially piecewise functions!

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Math Problem Analysis

Mathematical Concepts

Definite Integrals
Piecewise Functions
Geometric Interpretation of Area
Multiplication by a Scalar

Formulas

Area of a Triangle = \( \frac{1}{2} \times \text{base} \times \text{height} \)
Area of a Rectangle = \( \text{base} \times \text{height} \)

Theorems

Definite Integral Theorem for Piecewise Functions

Suitable Grade Level

Grades 10-12