Math Problem Statement

The graph of the derivative of a function is shown in the plot. Explain how the graph of the derivative relates to the behavior of the original function. Sketch a graph of the original function, assuming f(0) = 1.

Solution

To help with this question, let's break down the information from the image and solve it in steps.

Part 1: Explanation of the Derivative Graph

The graph provided shows the derivative f(x)f'(x) of some function f(x)f(x). The derivative graph appears to be a linear line with a positive slope.

  1. The derivative f(x)f'(x) is positive on the entire interval shown (for all values of xx where the graph lies above the x-axis). When f(x)f'(x) is positive, the original function f(x)f(x) is increasing.

  2. The derivative f(x)f'(x) is negative where the graph lies below the x-axis. In this graph, the derivative graph doesn’t go below the x-axis, so it’s always positive in this interval, meaning f(x)f(x) is always increasing.

  3. The derivative f(x)=0f'(x) = 0 at points where the graph crosses the x-axis. If it did cross, that would indicate possible local minima or maxima. However, in this case, the graph does not cross the x-axis, so there is no local minimum or maximum.

  4. The function is concave up when the derivative f(x)f'(x) is increasing. In this graph, the slope of the line is positive and constant, indicating that f(x)f(x) is concave up for the entire interval.

Based on these observations, the explanations for the behavior of the original function f(x)f(x) in relation to its derivative graph should be:

  • The function is increasing when the derivative is positive.
  • The function is concave up when the derivative is increasing.

Part 2: Sketching the Original Function f(x)f(x)

We’re given that f(0)=1f(0) = 1.

Since f(x)f'(x) is a positive, constant, and linear function (appearing as a sloped line), this suggests that the original function f(x)f(x) is a quadratic function that opens upwards (because it’s concave up). A reasonable form for f(x)f(x) could be something like f(x)=ax2+bx+cf(x) = ax^2 + bx + c.

Given that f(x)f'(x) is linear, let’s assume f(x)f(x) has a form such as f(x)=12x2+x+1f(x) = \frac{1}{2}x^2 + x + 1 or similar to match the constant rate of increase in f(x)f'(x).

For the sketch:

  1. At x=0x = 0, f(0)=1f(0) = 1, so plot the point (0,1)(0, 1).
  2. Since f(x)f(x) is concave up and increasing everywhere, draw a parabola that opens upwards, starting from (0,1)(0, 1).

Would you like me to provide further details or verify any specific part?


Here are some related questions you might explore:

  1. What is the general relationship between a function and its first derivative?
  2. How does the concavity of a function relate to the behavior of its second derivative?
  3. What is the impact of a constant positive derivative on the behavior of the original function?
  4. How would the graph of f(x)f(x) change if f(x)f'(x) had a negative slope?
  5. What types of functions have linear derivatives?

Tip: The first derivative's sign tells you if a function is increasing or decreasing, while its rate of change (second derivative) indicates concavity.

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Math Problem Analysis

Mathematical Concepts

Calculus
Derivatives
Function Behavior
Concavity
Increasing and Decreasing Functions

Formulas

f'(x): Derivative of f(x)
f(x) behavior from f'(x)

Theorems

First Derivative Test
Concavity and Second Derivative Test

Suitable Grade Level

High School - AP Calculus