Math Problem Statement

write a cubic function with points (-3,0), (-1,0), (2,0), and (-2,4)

Solution

To construct a cubic function f(x)f(x) with roots at x=3x = -3, x=1x = -1, and x=2x = 2, and passing through the point (2,4)(-2, 4), follow these steps:

  1. Form the general cubic function: Since the roots are 3-3, 1-1, and 22, the function can be written as: f(x)=a(x+3)(x+1)(x2)f(x) = a(x + 3)(x + 1)(x - 2) Here, aa is a constant to be determined using the additional point.

  2. Substitute the point (2,4)(-2, 4) into the function: Substitute x=2x = -2 and f(x)=4f(x) = 4: 4=a(2+3)(2+1)(22)4 = a(-2 + 3)(-2 + 1)(-2 - 2)

  3. Simplify to solve for aa: 4=a(1)(1)(4)4 = a(1)(-1)(-4) 4=4a4 = 4a a=1a = 1

  4. Write the final cubic function: Substituting a=1a = 1 into the general equation gives: f(x)=(x+3)(x+1)(x2)f(x) = (x + 3)(x + 1)(x - 2)

Final Answer:

f(x)=(x+3)(x+1)(x2)f(x) = (x + 3)(x + 1)(x - 2)

You can expand this if needed: f(x)=x3+2x25x6f(x) = x^3 + 2x^2 - 5x - 6


Would you like more details on this process or further clarification?
Here are some related questions you might explore:

  1. How can the cubic function be graphed to verify the points?
  2. How do you factorize a polynomial if roots are not integers?
  3. What is the role of the constant aa in polynomial scaling?
  4. How can we check if a cubic function passes through a given point?
  5. What changes in the function if one root is a double root?

Tip: Verify your cubic function by substituting all given points to ensure accuracy.

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Math Problem Analysis

Mathematical Concepts

Algebra
Polynomial Functions
Roots of Equations

Formulas

General form of a cubic polynomial: f(x) = a(x - r1)(x - r2)(x - r3)
Substitution of a point to find the constant: f(x) = a(x + 3)(x + 1)(x - 2)

Theorems

Root-Factor Theorem

Suitable Grade Level

Grades 9-12