Math Problem Statement

For the function f(x) = -5x^2 - 3x + 8, evaluate and fully simplify f(x + h) and (f(x + h) - f(x)) / h.

Solution

The function provided is f(x)=5x23x+8f(x) = -5x^2 - 3x + 8. We need to evaluate two expressions:

  1. f(x+h)f(x + h)
  2. f(x+h)f(x)h\frac{f(x + h) - f(x)}{h}

Let's break this down.

1. Finding f(x+h)f(x + h)

To compute f(x+h)f(x + h), substitute x+hx + h for xx in the function: f(x+h)=5(x+h)23(x+h)+8f(x + h) = -5(x + h)^2 - 3(x + h) + 8 Now, expand this expression:

(x+h)2=x2+2xh+h2(x + h)^2 = x^2 + 2xh + h^2 So, f(x+h)=5(x2+2xh+h2)3(x+h)+8f(x + h) = -5(x^2 + 2xh + h^2) - 3(x + h) + 8 Expanding further: f(x+h)=5x210xh5h23x3h+8f(x + h) = -5x^2 - 10xh - 5h^2 - 3x - 3h + 8

2. Finding f(x+h)f(x)h\frac{f(x + h) - f(x)}{h}

Now, subtract f(x)f(x) from f(x+h)f(x + h): f(x+h)f(x)=(5x210xh5h23x3h+8)(5x23x+8)f(x + h) - f(x) = (-5x^2 - 10xh - 5h^2 - 3x - 3h + 8) - (-5x^2 - 3x + 8) Simplify this: f(x+h)f(x)=10xh5h23hf(x + h) - f(x) = -10xh - 5h^2 - 3h Finally, divide by hh: f(x+h)f(x)h=10xh5h23hh\frac{f(x + h) - f(x)}{h} = \frac{-10xh - 5h^2 - 3h}{h} Simplify: f(x+h)f(x)h=10x5h3\frac{f(x + h) - f(x)}{h} = -10x - 5h - 3

Final answers:

  • f(x+h)=5x210xh5h23x3h+8f(x + h) = -5x^2 - 10xh - 5h^2 - 3x - 3h + 8
  • f(x+h)f(x)h=10x5h3\frac{f(x + h) - f(x)}{h} = -10x - 5h - 3

Would you like more details or clarifications on any of these steps?

Here are 5 related questions you might find useful:

  1. How do you find the derivative of f(x)=5x23x+8f(x) = -5x^2 - 3x + 8 using limits?
  2. What happens as h0h \to 0 in the difference quotient f(x+h)f(x)h\frac{f(x+h) - f(x)}{h}?
  3. How do you find the tangent line to f(x)f(x) at a given point?
  4. What is the significance of the difference quotient in calculus?
  5. How does expanding (x+h)2(x + h)^2 help in simplifying the difference quotient?

Tip: The difference quotient f(x+h)f(x)h\frac{f(x + h) - f(x)}{h} is the foundation for finding the derivative, which represents the slope of the tangent line to the function at any point xx.

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Math Problem Analysis

Mathematical Concepts

Functions
Difference Quotient
Polynomials
Algebra

Formulas

f(x + h) = -5(x + h)^2 - 3(x + h) + 8
Difference Quotient: (f(x + h) - f(x)) / h

Theorems

Limit Definition of Derivative

Suitable Grade Level

Grades 10-12 (High School Calculus)