Math Problem Statement

Compute and simplify the difference quotient (f(x+h) - f(x)) / h for the function f(x) = 5x^2 - 3x - 7.

Solution

Let's compute the difference quotient for the given function:

The function is: f(x)=5x23x7f(x) = 5x^2 - 3x - 7

The difference quotient is defined as: f(x+h)f(x)h\frac{f(x+h) - f(x)}{h}

Step 1: Find f(x+h)f(x+h)

We substitute x+hx+h into the function: f(x+h)=5(x+h)23(x+h)7f(x+h) = 5(x+h)^2 - 3(x+h) - 7 Expand (x+h)2(x+h)^2: (x+h)2=x2+2xh+h2(x+h)^2 = x^2 + 2xh + h^2 Thus: f(x+h)=5(x2+2xh+h2)3(x+h)7f(x+h) = 5(x^2 + 2xh + h^2) - 3(x+h) - 7 Expanding: f(x+h)=5x2+10xh+5h23x3h7f(x+h) = 5x^2 + 10xh + 5h^2 - 3x - 3h - 7

Step 2: Compute f(x+h)f(x)f(x+h) - f(x)

Now, subtract f(x)f(x) from f(x+h)f(x+h): f(x+h)f(x)=(5x2+10xh+5h23x3h7)(5x23x7)f(x+h) - f(x) = \left( 5x^2 + 10xh + 5h^2 - 3x - 3h - 7 \right) - \left( 5x^2 - 3x - 7 \right) Simplifying: f(x+h)f(x)=5x2+10xh+5h23x3h75x2+3x+7f(x+h) - f(x) = 5x^2 + 10xh + 5h^2 - 3x - 3h - 7 - 5x^2 + 3x + 7 Canceling out terms: f(x+h)f(x)=10xh+5h23hf(x+h) - f(x) = 10xh + 5h^2 - 3h

Step 3: Divide by hh

Now, divide the result by hh: f(x+h)f(x)h=10xh+5h23hh\frac{f(x+h) - f(x)}{h} = \frac{10xh + 5h^2 - 3h}{h} Simplify: f(x+h)f(x)h=10x+5h3\frac{f(x+h) - f(x)}{h} = 10x + 5h - 3

Final Answer:

The simplified difference quotient is: 10x+5h3\boxed{10x + 5h - 3}

Would you like further details or clarifications?


Here are 5 related questions to expand on this concept:

  1. How is the difference quotient related to the derivative?
  2. What happens to the expression when h0h \to 0?
  3. How would the difference quotient change if the function were cubic, for example, f(x)=2x35x+1f(x) = 2x^3 - 5x + 1?
  4. Can you compute the derivative of the given function f(x)=5x23x7f(x) = 5x^2 - 3x - 7?
  5. How does the difference quotient represent the average rate of change?

Tip: The difference quotient formula is a foundational concept for understanding derivatives, which measure the instantaneous rate of change of a function.

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Math Problem Analysis

Mathematical Concepts

Algebra
Calculus
Difference Quotient

Formulas

Difference quotient: (f(x+h) - f(x)) / h

Theorems

Concept of Average Rate of Change

Suitable Grade Level

Grades 11-12