Math Problem Statement

Use the definition of the derivative to find the derivative of f(x) = 9x + 11.

Solution

To find the derivative of the function f(x)=9x+11f(x) = 9x + 11 using the definition of the derivative, we use the following formula:

f(x)=limh0f(x+h)f(x)hf'(x) = \lim_{h \to 0} \frac{f(x+h) - f(x)}{h}

Step-by-Step Solution:

  1. Find f(x+h)f(x+h): f(x+h)=9(x+h)+11=9x+9h+11f(x+h) = 9(x+h) + 11 = 9x + 9h + 11

  2. Substitute into the definition: f(x)=limh0(9x+9h+11)(9x+11)hf'(x) = \lim_{h \to 0} \frac{(9x + 9h + 11) - (9x + 11)}{h} Simplify the numerator: f(x)=limh09x+9h+119x11h=limh09hhf'(x) = \lim_{h \to 0} \frac{9x + 9h + 11 - 9x - 11}{h} = \lim_{h \to 0} \frac{9h}{h}

  3. Simplify the expression: f(x)=limh09=9f'(x) = \lim_{h \to 0} 9 = 9

Thus, the derivative of f(x)=9x+11f(x) = 9x + 11 is:

f(x)=9f'(x) = 9

Would you like further explanation or details on the concept of derivatives?

Here are 5 related questions to explore:

  1. How do you compute the derivative of a quadratic function using the definition?
  2. What is the geometric interpretation of the derivative?
  3. How is the derivative of a constant function computed?
  4. Can the definition of the derivative be used to find second derivatives?
  5. How does the derivative relate to the slope of a tangent line at a given point?

Tip: When differentiating linear functions, the derivative is simply the coefficient of xx since the rate of change is constant.

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Math Problem Analysis

Mathematical Concepts

Calculus
Derivatives
Limits

Formulas

f'(x) = lim(h -> 0) [(f(x + h) - f(x)) / h]

Theorems

Definition of the derivative

Suitable Grade Level

Grade 11-12