Math Problem Statement

Find the limit of the difference quotient for the function f(x) = 8x^2 - 5x.

Solution

The problem asks for the limit of a difference quotient, which represents the derivative of the function f(x)=8x25xf(x) = 8x^2 - 5x. Specifically, it is asking for:

limΔx0f(x+Δx)f(x)Δx\lim_{\Delta x \to 0} \frac{f(x + \Delta x) - f(x)}{\Delta x}

Steps to solve this:

  1. Find f(x+Δx)f(x + \Delta x):

    • Given f(x)=8x25xf(x) = 8x^2 - 5x, substitute x+Δxx + \Delta x into the function.
    • f(x+Δx)=8(x+Δx)25(x+Δx)f(x + \Delta x) = 8(x + \Delta x)^2 - 5(x + \Delta x).
  2. Expand the expression:

    • Expand (x+Δx)2(x + \Delta x)^2 to get x2+2xΔx+(Δx)2x^2 + 2x\Delta x + (\Delta x)^2.
    • Substitute back into the function: [ f(x + \Delta x) = 8(x^2 + 2x\Delta x + (\Delta x)^2) - 5(x + \Delta x). \

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Limits
Derivatives
Difference Quotients
Polynomials

Formulas

f(x) = 8x^2 - 5x
Limit definition of derivative: lim(Δx → 0) [f(x + Δx) - f(x)] / Δx

Theorems

Limit Definition of a Derivative

Suitable Grade Level

Grades 11-12