Math Problem Statement

y = 2x³ - 5

Solution

The given equation is:

y=2x35y = 2x^3 - 5

This is a cubic function. Let's break down some important features:

  1. Type of Function: It is a cubic function because the highest power of xx is 3.
  2. Intercepts:
    • Y-intercept: The point where x=0x = 0, which is y=2(0)35=5y = 2(0)^3 - 5 = -5. So, the y-intercept is (0,5)(0, -5).
    • X-intercept: To find the x-intercept(s), set y=0y = 0 and solve for xx: 0=2x35x3=52x=5230 = 2x^3 - 5 \quad \Rightarrow \quad x^3 = \frac{5}{2} \quad \Rightarrow \quad x = \sqrt[3]{\frac{5}{2}} So, the x-intercept is x=523x = \sqrt[3]{\frac{5}{2}}, which is approximately x1.3572x \approx 1.3572.
  3. Slope/Rate of Change: Since it's a cubic function, the slope is not constant. The slope increases as xx increases because the derivative is positive for large values of xx.
  4. Derivative: To understand the rate of change or the slope at any point, we can take the derivative: dydx=6x2\frac{dy}{dx} = 6x^2 This shows that the slope is positive for all xx, except when x=0x = 0, where the slope is 0 (indicating a critical point).
  5. Critical Points and Behavior: There is a critical point at x=0x = 0 because the derivative equals 0 there. Since the slope changes from negative to positive as we pass through x=0x = 0, this point represents a local minimum.

Would you like further details on any specific aspect of this function?

Here are 5 questions to explore further:

  1. How do we find the second derivative and what does it tell us about the function's concavity?
  2. Can you explain how to sketch the graph of this cubic function?
  3. What happens as xx approaches positive and negative infinity in this function?
  4. Can you calculate the inflection points for the function y=2x35y = 2x^3 - 5?
  5. How would we solve the equation 2x35=02x^3 - 5 = 0 exactly?

Tip: For cubic functions, understanding the derivative helps reveal crucial details about local extrema and points of inflection.

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Math Problem Analysis

Mathematical Concepts

Algebra
Cubic Functions
Derivatives
Intercepts
Critical Points

Formulas

Cubic function: y = ax^3 + bx^2 + cx + d
Y-intercept: Set x = 0
X-intercept: Solve y = 0
Derivative: dy/dx = 6x^2

Theorems

Critical points and local extrema via derivatives

Suitable Grade Level

Grades 10-12