Math Problem Statement

Evaluate g(2) where g(x) = ∫_{-2}^x f(t) dt, given the graph of f(t).

Solution

To evaluate g(2)g(2), where g(x)=2xf(t)dtg(x) = \int_{-2}^x f(t) \, dt, we need to find the area under the curve f(t)f(t) from t=2t = -2 to t=2t = 2.

Here is the step-by-step process:

Step 1: Analyze the graph

The graph of f(t)f(t) is made of line segments. We will calculate the areas of the regions between t=2t = -2 and t=2t = 2, remembering:

  • Areas above the tt-axis contribute positively.
  • Areas below the tt-axis contribute negatively.

Step 2: Break the integral into sub-intervals

The interval from t=2t = -2 to t=2t = 2 is divided into the following regions based on the graph:

  1. From t=2t = -2 to t=0t = 0: a trapezoid.
  2. From t=0t = 0 to t=2t = 2: a rectangle and a triangle.

Step 3: Calculate each area

  1. From t=2t = -2 to t=0t = 0:
    The trapezoid has bases of y=2y = 2 and y=4y = 4, with a width of 2.
    Area = 12×(base1+base2)×width=12×(2+4)×2=6\frac{1}{2} \times (\text{base}_1 + \text{base}_2) \times \text{width} = \frac{1}{2} \times (2 + 4) \times 2 = 6.

  2. From t=0t = 0 to t=2t = 2:

    • The rectangle has a height of 4 and a width of 2.
      Area = 4×2=84 \times 2 = 8.

Step 4: Add areas

The total area from t=2t = -2 to t=2t = 2 is: g(2)=6+8=14.g(2) = 6 + 8 = 14.

Final Answer:

g(2)=14.g(2) = 14.

Would you like a more detailed breakdown or further clarifications?


Related Questions:

  1. What is the value of g(0)g(0) using the same graph?
  2. How does g(x)g'(x) relate to f(x)f(x) in this scenario?
  3. How would you interpret g(x)g(x) if f(x)f(x) were negative?
  4. What is the significance of the Fundamental Theorem of Calculus in this context?
  5. How would you calculate g(4)g(4) for this function?

Tip:

Always pay attention to the signs of the areas (positive above the axis, negative below) when dealing with definite integrals!

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Math Problem Analysis

Mathematical Concepts

Definite Integrals
Area Under the Curve
Piecewise Functions

Formulas

g(x) = ∫_{-2}^x f(t) dt
Area of trapezoid: (1/2) × (base_1 + base_2) × height
Area of rectangle: width × height

Theorems

Fundamental Theorem of Calculus

Suitable Grade Level

Grades 11-12