Math Problem Statement

f(x)=-3x^3+2x^2+7x-8 when x=-2

Solution

To evaluate the function f(x)=3x3+2x2+7x8f(x) = -3x^3 + 2x^2 + 7x - 8 at x=2x = -2, substitute 2-2 into the equation for xx:

f(2)=3(2)3+2(2)2+7(2)8f(-2) = -3(-2)^3 + 2(-2)^2 + 7(-2) - 8

Step-by-Step Calculation:

  1. Calculate (2)3(-2)^3: (2)3=8(-2)^3 = -8

    Substitute: f(2)=3(8)+2(2)2+7(2)8f(-2) = -3(-8) + 2(-2)^2 + 7(-2) - 8

  2. Calculate (2)2(-2)^2: (2)2=4(-2)^2 = 4

    Substitute: f(2)=3(8)+2(4)+7(2)8f(-2) = -3(-8) + 2(4) + 7(-2) - 8

  3. Simplify each term:

    • 3(8)=24-3(-8) = 24
    • 2(4)=82(4) = 8
    • 7(2)=147(-2) = -14
    • Constant term: 8-8

    Combine: f(2)=24+8148f(-2) = 24 + 8 - 14 - 8

  4. Add/Subtract the terms: f(2)=24+8=32f(-2) = 24 + 8 = 32 3214=1832 - 14 = 18 188=1018 - 8 = 10

Final Answer:

f(2)=10f(-2) = 10

Let me know if you want further clarification or additional examples.


Related Questions:

  1. How does the degree of the polynomial affect its shape?
  2. What are the roots of f(x)=3x3+2x2+7x8f(x) = -3x^3 + 2x^2 + 7x - 8?
  3. How do you find the derivative of f(x)f(x)?
  4. How can you determine where this function is increasing or decreasing?
  5. How do you evaluate f(x)f(x) for a fractional value of xx?

Tip:

When substituting into polynomial functions, be careful with the signs, especially when dealing with negative exponents or odd powers!

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Math Problem Analysis

Mathematical Concepts

Algebra
Polynomial Functions
Function Evaluation

Formulas

f(x) = ax^3 + bx^2 + cx + d

Theorems

Substitution Method for Evaluating Functions

Suitable Grade Level

Grades 9-12