Math Problem Statement

If f(x) = 2 + 4x - 5x^2, find f'(-4).

Solution

To solve the problem, we are given the function:

f(x)=2+4x5x2f(x) = 2 + 4x - 5x^2

and asked to find f(4)f'(-4), which is the value of the derivative of the function at x=4x = -4.

Steps:

  1. Differentiate the function f(x)f(x) with respect to xx:

    f(x)=ddx(2+4x5x2)f'(x) = \frac{d}{dx} \left( 2 + 4x - 5x^2 \right)

    • The derivative of a constant (2) is 0.
    • The derivative of 4x4x is 4.
    • The derivative of 5x2-5x^2 is 10x-10x (using the power rule).

    Thus, the derivative is:

    f(x)=410xf'(x) = 4 - 10x

  2. Substitute x=4x = -4 into the derivative:

    f(4)=410(4)f'(-4) = 4 - 10(-4) f(4)=4+40=44f'(-4) = 4 + 40 = 44

Final Answer:

f(4)=44f'(-4) = 44

Would you like any further details on this problem?


Here are 5 related questions you might want to consider:

  1. How do you apply the power rule for differentiation?
  2. What are the steps for differentiating polynomial functions?
  3. How do you find the second derivative of a function?
  4. How do derivatives relate to the slope of the tangent line at a point?
  5. Can you interpret the physical meaning of a derivative in real-world problems?

Tip: Always check your derivative calculations by simplifying each term carefully before evaluating at a specific point.

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Math Problem Analysis

Mathematical Concepts

Differentiation
Polynomials

Formulas

f'(x) = d/dx [f(x)]
Power rule: d/dx [x^n] = n * x^(n-1)

Theorems

Power Rule for Differentiation

Suitable Grade Level

Grades 10-12 (High School Calculus)