Math Problem Statement

Let \( g(x) = \int_0^x f(t) \ dt \), where \( f \) is the function whose graph is shown. Evaluate \( g(x) \) for specific values of \( x \), estimate \( g(35) \) using the midpoint method, and determine the minimum and maximum of \( g(x) \).

Solution

Let's go through each part of the problem.

Problem Interpretation

You’re given a function g(x)=0xf(t)dtg(x) = \int_0^x f(t) \, dt, where ff is represented by the provided graph. We need to evaluate g(x)g(x) at specified values by approximating the area under ff from t=0t = 0 to t=xt = x. Since the graph of ff does not have an explicit formula, we'll approximate these areas by calculating the areas of geometric shapes (like triangles and rectangles) formed under the curve.

Step-by-Step Solution

(a) Evaluate g(x)g(x) for x=0,5,10,15,20,25,x = 0, 5, 10, 15, 20, 25, and 3030.

  1. g(0)=0g(0) = 0
    Since g(0)g(0) represents the integral from 00 to 00, it has no area under the curve, so g(0)=0g(0) = 0.

  2. g(5)g(5)
    From 00 to 55, we have a triangle below the x-axis with a base of 5 and height of approximately -4.
    Area =12×5×(4)=10= \frac{1}{2} \times 5 \times (-4) = -10.
    Thus, g(5)=10g(5) = -10.

  3. g(10)g(10)
    From 55 to 1010, we have a triangle above the x-axis with a base of 5 and height of approximately 4.
    Area =12×5×4=10= \frac{1}{2} \times 5 \times 4 = 10.
    Adding this to g(5)g(5), we get g(10)=10+10=0g(10) = -10 + 10 = 0.

  4. g(15)g(15)
    From 1010 to 1515, we have a triangle below the x-axis with a base of 5 and height of -3.
    Area =12×5×(3)=7.5= \frac{1}{2} \times 5 \times (-3) = -7.5.
    Thus, g(15)=07.5=7.5g(15) = 0 - 7.5 = -7.5.

  5. g(20)g(20)
    From 1515 to 2020, we have a rectangle above the x-axis with a base of 5 and height of 3.
    Area =5×3=15= 5 \times 3 = 15.
    Adding this to g(15)g(15), we get g(20)=7.5+15=7.5g(20) = -7.5 + 15 = 7.5.

  6. g(25)g(25)
    From 2020 to 2525, we have a triangle above the x-axis with a base of 5 and height of 5.
    Area =12×5×5=12.5= \frac{1}{2} \times 5 \times 5 = 12.5.
    Thus, g(25)=7.5+12.5=20g(25) = 7.5 + 12.5 = 20.

  7. g(30)g(30)
    From 2525 to 3030, we have a triangle below the x-axis with a base of 5 and height of -5.
    Area =12×5×(5)=12.5= \frac{1}{2} \times 5 \times (-5) = -12.5.
    Thus, g(30)=2012.5=7.5g(30) = 20 - 12.5 = 7.5.

(b) Estimate g(35)g(35).

Using the midpoint method, we’ll approximate the area from 3030 to 3535 with the average height of ff in that interval, which appears to be around 2.
Approximate area from 3030 to 35=5×2=1035 = 5 \times 2 = 10.
Thus, g(35)7.5+10=17.5g(35) \approx 7.5 + 10 = 17.5.

(c) Identify where gg has a maximum and minimum value.

Based on the calculations in part (a):

  • Minimum value occurs at x=15x = 15 with g(15)=7.5g(15) = -7.5.
  • Maximum value occurs at x=25x = 25 with g(25)=20g(25) = 20.

Final Answers

  • (a)
    g(0)=0g(0) = 0
    g(5)=10g(5) = -10
    g(10)=0g(10) = 0
    g(15)=7.5g(15) = -7.5
    g(20)=7.5g(20) = 7.5
    g(25)=20g(25) = 20
    g(30)=7.5g(30) = 7.5

  • (b)
    g(35)17.5g(35) \approx 17.5

  • (c)
    Minimum at x=15x = 15 with g(15)=7.5g(15) = -7.5
    Maximum at x=25x = 25 with g(25)=20g(25) = 20

Would you like more details on any of these steps?

Additional Related Questions

  1. How would changing the heights of the peaks in f(t)f(t) affect the values of g(x)g(x)?
  2. What does the function g(x)g(x) represent in terms of accumulated area?
  3. How could we approximate g(x)g(x) if f(t)f(t) had irregular shapes instead of straight-line segments?
  4. What happens to g(x)g(x) if f(t)f(t) were shifted vertically?
  5. Can we determine the concavity of g(x)g(x) from the graph of f(x)f(x)?

Tip

When working with integrals that represent areas, visualize each segment carefully and remember that areas below the x-axis are negative.

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Math Problem Analysis

Mathematical Concepts

Integral Calculus
Definite Integrals
Area Under a Curve
Approximations

Formulas

\( g(x) = \int_0^x f(t) \ dt \)

Theorems

Fundamental Theorem of Calculus

Suitable Grade Level

Grades 11-12