Math Problem Statement

Given the function f(x) = -2 - x^2, express the value of (f(x+h) - f(x)) / h in simplest form.

Solution

We are given the function f(x)=2x2f(x) = -2 - x^2 and asked to express the value of

f(x+h)f(x)h\frac{f(x+h) - f(x)}{h}

in its simplest form. This expression is a difference quotient, often used to calculate the derivative of a function.

Let's solve this step by step.

  1. Find f(x+h)f(x+h): Start by substituting x+hx+h into the function f(x)=2x2f(x) = -2 - x^2.

    f(x+h)=2(x+h)2f(x+h) = -2 - (x+h)^2 Expand (x+h)2(x+h)^2: (x+h)2=x2+2xh+h2(x+h)^2 = x^2 + 2xh + h^2 So, f(x+h)=2(x2+2xh+h2)=2x22xhh2f(x+h) = -2 - (x^2 + 2xh + h^2) = -2 - x^2 - 2xh - h^2

  2. Subtract f(x)f(x): Now, subtract f(x)=2x2f(x) = -2 - x^2 from f(x+h)f(x+h): f(x+h)f(x)=(2x22xhh2)(2x2)f(x+h) - f(x) = \left( -2 - x^2 - 2xh - h^2 \right) - \left( -2 - x^2 \right) Simplifying: f(x+h)f(x)=2x22xhh2+2+x2f(x+h) - f(x) = -2 - x^2 - 2xh - h^2 + 2 + x^2 The 2-2 and +2+2 cancel out, and x2-x^2 and +x2+x^2 cancel out, leaving: f(x+h)f(x)=2xhh2f(x+h) - f(x) = -2xh - h^2

  3. Divide by hh: Finally, divide the result by hh: f(x+h)f(x)h=2xhh2h\frac{f(x+h) - f(x)}{h} = \frac{-2xh - h^2}{h} Simplify by dividing each term by hh: f(x+h)f(x)h=2xh\frac{f(x+h) - f(x)}{h} = -2x - h

Thus, the simplified form of the difference quotient is:

f(x+h)f(x)h=2xh\frac{f(x+h) - f(x)}{h} = -2x - h

Would you like further explanation or have any questions?

Here are 5 related questions to expand your understanding:

  1. What is the purpose of the difference quotient in calculus?
  2. How would you calculate the derivative of the function f(x)=2x2f(x) = -2 - x^2 directly?
  3. What happens to the difference quotient as hh approaches 0?
  4. Can you explain the geometric interpretation of the difference quotient?
  5. How is the difference quotient related to the slope of a secant line?

Tip: The difference quotient is a critical step in deriving the concept of a derivative, which measures the instantaneous rate of change of a function.

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Math Problem Analysis

Mathematical Concepts

Calculus
Difference Quotient
Functions

Formulas

f(x) = -2 - x^2
Difference Quotient: (f(x+h) - f(x)) / h

Theorems

Definition of the Derivative
Limit of the Difference Quotient

Suitable Grade Level

Grades 10-12