Math Problem Statement

Find the difference quotient of f(x) = x^2 - 5x + 1, that is, find \( \frac{f(x+h) - f(x)}{h} \), h \neq 0, and simplify.

Solution

We are tasked with finding the difference quotient for the function f(x)=x25x+1f(x) = x^2 - 5x + 1. The difference quotient is given by:

f(x+h)f(x)h,h0.\frac{f(x+h) - f(x)}{h}, \quad h \neq 0.

Step-by-step Solution:

  1. Substitute f(x+h)f(x+h): Replace xx with x+hx+h in f(x)f(x): f(x+h)=(x+h)25(x+h)+1.f(x+h) = (x+h)^2 - 5(x+h) + 1. Expand each term: f(x+h)=x2+2xh+h25x5h+1.f(x+h) = x^2 + 2xh + h^2 - 5x - 5h + 1.

  2. Subtract f(x)f(x): Write f(x+h)f(x)f(x+h) - f(x): f(x+h)f(x)=(x2+2xh+h25x5h+1)(x25x+1).f(x+h) - f(x) = \left(x^2 + 2xh + h^2 - 5x - 5h + 1\right) - \left(x^2 - 5x + 1\right). Simplify by canceling terms: f(x+h)f(x)=2xh+h25h.f(x+h) - f(x) = 2xh + h^2 - 5h.

  3. Divide by hh: Substitute f(x+h)f(x)f(x+h) - f(x) into the difference quotient: f(x+h)f(x)h=2xh+h25hh.\frac{f(x+h) - f(x)}{h} = \frac{2xh + h^2 - 5h}{h}. Simplify each term by dividing through by hh: f(x+h)f(x)h=2x+h5.\frac{f(x+h) - f(x)}{h} = 2x + h - 5.

Final Answer:

f(x+h)f(x)h=2x+h5.\frac{f(x+h) - f(x)}{h} = 2x + h - 5.

Would you like me to expand further on any part of this solution or provide more context?


Here are five related questions to expand your understanding:

  1. How is the difference quotient related to the derivative of a function?
  2. What does the term h0h \to 0 mean in calculus?
  3. Can the difference quotient be used for functions with discontinuities? Why or why not?
  4. What would f(x+h)f(x)f(x+h) - f(x) look like for a cubic function f(x)=x3f(x) = x^3?
  5. How do you interpret 2x+h52x + h - 5 geometrically for the given quadratic?

Tip:

When simplifying expressions, always organize like terms step by step to avoid mistakes!

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Math Problem Analysis

Mathematical Concepts

Algebra
Difference Quotient
Quadratic Functions

Formulas

Difference Quotient Formula: \( \frac{f(x+h) - f(x)}{h} \)

Theorems

Concept of Slope of a Secant Line

Suitable Grade Level

Grade 10-12 (High School Pre-Calculus)