Math Problem Statement

Calculate the limit for the function f(x) = (7/2)x + 4 over the interval [0, 4]. Verify your answer by using geometry.

Solution

To solve this, we need to calculate the limit of the function f(x)=72x+4f(x) = \frac{7}{2}x + 4 over the interval [0,4][0, 4] and verify the result using geometry.

Step 1: Define the function and the interval

The function is f(x)=72x+4f(x) = \frac{7}{2}x + 4. The interval is [0,4][0, 4].

Step 2: Evaluate the function at the endpoints

At x=0x = 0: f(0)=72(0)+4=4f(0) = \frac{7}{2}(0) + 4 = 4

At x=4x = 4: f(4)=72(4)+4=14+4=18f(4) = \frac{7}{2}(4) + 4 = 14 + 4 = 18

Step 3: Geometric interpretation

The graph of f(x)=72x+4f(x) = \frac{7}{2}x + 4 is a straight line with a slope of 72\frac{7}{2} and a y-intercept at 4. Over the interval [0,4][0, 4], the line rises from f(0)=4f(0) = 4 to f(4)=18f(4) = 18.

To calculate the area under the curve geometrically, the area forms a trapezoid. The trapezoid's parallel sides are the values of f(x)f(x) at the endpoints (44 and 1818), and the base length is the interval length (44).

Step 4: Calculate the area of the trapezoid

The formula for the area of a trapezoid is: Area=12×(Base1+Base2)×Height\text{Area} = \frac{1}{2} \times (\text{Base}_1 + \text{Base}_2) \times \text{Height} Here:

  • Base1=4\text{Base}_1 = 4 (value of f(0)f(0)),
  • Base2=18\text{Base}_2 = 18 (value of f(4)f(4)),
  • Height=4\text{Height} = 4 (interval length).

Area=12×(4+18)×4=12×22×4=44\text{Area} = \frac{1}{2} \times (4 + 18) \times 4 = \frac{1}{2} \times 22 \times 4 = 44

Final Answer:

The limit of the function f(x)f(x) over the interval [0,4][0, 4], calculated geometrically, is: 44\boxed{44}

Do you have any questions or would you like further clarification on any part of the solution?


Here are 5 related questions for deeper exploration:

  1. What is the derivative of f(x)=72x+4f(x) = \frac{7}{2}x + 4 and how does it relate to the slope?
  2. How does the geometric area under a curve relate to the integral of the function?
  3. Can this approach be extended to non-linear functions? How would the calculation differ?
  4. What is the significance of the line equation f(x)=mx+bf(x) = mx + b in geometry?
  5. How does this problem illustrate the relationship between algebra and geometry?

Tip: Always visualize a problem graphically when possible—it can make abstract concepts clearer!

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Math Problem Analysis

Mathematical Concepts

Limits
Algebra
Geometry
Linear Functions

Formulas

Area of a trapezoid: Area = (1/2) * (Base1 + Base2) * Height
Equation of a line: f(x) = mx + b

Theorems

Geometric interpretation of integrals

Suitable Grade Level

Grades 10-12