Math Problem Statement

Find the following limit for f(x) = 7x - 3: lim(h→0) [f(2+h) - f(2)] / h

Solution

To solve this problem, we need to evaluate the limit:

limh0f(2+h)f(2)h\lim_{h \to 0} \frac{f(2+h) - f(2)}{h}

This expression represents the derivative of f(x)=7x3f(x) = 7x - 3 at x=2x = 2.

Step 1: Find f(2)f(2)

Using the function f(x)=7x3f(x) = 7x - 3: f(2)=723=143=11f(2) = 7 \cdot 2 - 3 = 14 - 3 = 11

Step 2: Find f(2+h)f(2 + h)

Substitute x=2+hx = 2 + h into f(x)=7x3f(x) = 7x - 3: f(2+h)=7(2+h)3=14+7h3=11+7hf(2 + h) = 7(2 + h) - 3 = 14 + 7h - 3 = 11 + 7h

Step 3: Set up the limit expression

Now substitute f(2+h)f(2 + h) and f(2)f(2) into the difference quotient: f(2+h)f(2)h=(11+7h)11h=7hh\frac{f(2+h) - f(2)}{h} = \frac{(11 + 7h) - 11}{h} = \frac{7h}{h}

Step 4: Simplify the expression

\frac{7h}{h} = 7 \quad \text{(for h \neq 0)}

Step 5: Take the limit as h0h \to 0

Since there are no hh-terms left, the limit is: limh0f(2+h)f(2)h=7\lim_{h \to 0} \frac{f(2+h) - f(2)}{h} = 7

Final Answer

7\boxed{7}

Would you like more details, or do you have any questions?

Related Questions

  1. How would the answer change if f(x)=7x+3f(x) = 7x + 3 instead of 7x37x - 3?
  2. Can you find the derivative of f(x)=ax+bf(x) = ax + b at any point x=cx = c?
  3. What does the derivative of a linear function represent geometrically?
  4. How would you apply the limit definition of a derivative to a quadratic function, like f(x)=x2f(x) = x^2?
  5. How can you compute the derivative of f(x)=7x3f(x) = 7x - 3 using the power rule instead?

Tip

When dealing with linear functions, their derivatives are constants because they represent the slope of the line across all values of xx.

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Math Problem Analysis

Mathematical Concepts

Limits
Derivatives
Linear Functions

Formulas

Limit definition of derivative: lim(h→0) [f(a+h) - f(a)] / h
Derivative of a linear function f(x) = mx + b is m

Theorems

Limit definition of the derivative

Suitable Grade Level

Grades 11-12