Math Problem Statement

Sketch a graph of f(x) = x^3 - 5.

Solution

The task asks to sketch the graph of the function f(x)=x35f(x) = x^3 - 5. Here's a step-by-step explanation to help sketch this graph:

Step 1: Understand the Function

The function f(x)=x35f(x) = x^3 - 5 is a cubic function. Its general shape will resemble an x3x^3 curve but shifted vertically down by 5 units due to the 5-5.

Step 2: Key Features

  1. Intercepts:

    • Y-intercept: Set x=0x = 0: f(0)=035=5.f(0) = 0^3 - 5 = -5. The y-intercept is (0,5)(0, -5).
    • X-intercept: Set f(x)=0f(x) = 0: x35=0x3=5x=53.x^3 - 5 = 0 \quad \Rightarrow \quad x^3 = 5 \quad \Rightarrow \quad x = \sqrt[3]{5}. Approximate x1.71x \approx 1.71.
  2. End Behavior:

    • As xx \to \infty, f(x)f(x) \to \infty.
    • As xx \to -\infty, f(x)f(x) \to -\infty.
  3. Symmetry:

    • The function is not symmetric because it is neither even nor odd.

Step 3: Plot Points

Calculate several points to better sketch the curve:

  • f(2)=(2)35=85=13f(-2) = (-2)^3 - 5 = -8 - 5 = -13.
  • f(1)=(1)35=6f(-1) = (-1)^3 - 5 = -6.
  • f(0)=5f(0) = -5.
  • f(1)=135=4f(1) = 1^3 - 5 = -4.
  • f(2)=235=85=3f(2) = 2^3 - 5 = 8 - 5 = 3.

Step 4: Sketch the Graph

  1. Plot the calculated points (2,13),(1,6),(0,5),(1,4),(2,3)(-2, -13), (-1, -6), (0, -5), (1, -4), (2, 3).
  2. Draw a smooth curve passing through these points, keeping the end behavior and cubic shape in mind.

Would you like me to provide a detailed plot or clarify any of the steps?


Questions for Practice:

  1. How does the graph of f(x)=x35f(x) = x^3 - 5 differ from f(x)=x3f(x) = x^3?
  2. Find the slope of the tangent line to the curve at x=2x = 2.
  3. Determine whether f(x)=x35f(x) = x^3 - 5 has any points of inflection.
  4. What is the derivative of f(x)f(x), and how does it help in analyzing the curve?
  5. Sketch f(x)=x3+5f(x) = x^3 + 5 and compare it with f(x)=x35f(x) = x^3 - 5.

Tip:

For polynomial functions, always start by analyzing their intercepts, end behavior, and turning points to understand the overall graph shape.

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Math Problem Analysis

Mathematical Concepts

Graphing Polynomial Functions
Cubic Functions
Transformations

Formulas

f(x) = x^3 - 5

Theorems

End Behavior of Polynomials
Intercepts of Functions

Suitable Grade Level

Grades 9-12