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91Ó°ÊÓ

Find the average rate of change of the function from \(x_{1}\) to \(x_{2}\). $$ \text {Function} \quad \text {x-Values}$$ $$ f(x)=x^{2}+12 x-4 \quad x_{1}=1, x_{2}=5 $$

Short Answer

Expert verified
The average rate of change of the function from \(x_{1}\) to \(x_{2}\) is 13.

Step by step solution

01

Substitution of \(x_{1}\) into \(f(x)\)

First, let's find the function values for \(x_{1}\) which is 1. Plug \(x_{1} = 1\) into the function, \(f(x) = x^{2}+12x-4\), yielding: \(f(x_{1}) = (1)^{2} + 12*1 - 4 = 9\)
02

Substitution of \(x_{2}\) into \(f(x)\)

Next, let's find the function values for \(x_{2}\) which is 5. Plug \(x_{2} = 5\) into the function, \(f(x) = x^{2}+12x-4\), yielding: \(f(x_{2}) = (5)^{2} + 12*5 - 4 = 61\)
03

Calculation of the Average Rate of Change

Now that we have both \(f(x_{1})\) and \(f(x_{2})\), let's calculate the average rate of change using the formula \((f(x_{2}) - f(x_{1})) / (x_{2} - x_{1})\). This results to: \((61 - 9) / (5 - 1) = 52/4 = 13\).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Function Evaluation
To evaluate a function, we must substitute given values into the function equation to determine their specific outputs. Imagine a function as a machine that processes inputs to produce outputs. If we know the input, in our case specific x-values, we can find the corresponding output or "function value."
  • Identify the given x-values: In our exercise, these are \(x_1 = 1\) and \(x_2 = 5\).
  • Input each x-value into the function \(f(x) = x^2 + 12x - 4\).
  • Calculate the output values, which are \(f(1)\) and \(f(5)\).
Function evaluation helps determine values necessary for further procedures like finding rates of change.
Substitution
Substitution is a straightforward yet crucial mathematical technique used when evaluating functions. It involves replacing variables with specific values or expressions to simplify the function and facilitate calculations.
In the context of evaluating a quadratic function:
  • Write the function: \(f(x) = x^2 + 12x - 4\).
  • Substitute the x-value, such as \(x=1\) or \(x=5\).
  • Replace every instance of the variable x with the given number in the equation.
  • Calculate the result of the newly simplified expression.
Substitution tells us exactly what a specific part of the function looks like when x reaches a particular value, providing crucial insights into the function's behavior.
Quadratic Functions
Quadratic functions form an essential class of polynomial functions, defined by their standard form \(f(x) = ax^2 + bx + c\), where \(a\), \(b\), and \(c\) are constants, and \(a \/neq 0\).
These functions graph as parabolas, exhibiting various characteristics:
  • Vertex: The highest or lowest point on the graph.
  • Axis of Symmetry: A line that divides the parabola into two mirror images, running vertically through the vertex.
  • Opening direction: Upward if \(a > 0\) and downward if \(a < 0\).
Analyzing a quadratic function like \(f(x) = x^2 + 12x - 4\) reveals its shape and behavior, crucial for calculating rates like changes over specific intervals.
Rate of Change Formula
The rate of change formula is used to gauge how a function value changes as the x-value changes over an interval. This is the essence of calculating average rates of change.
The formula used is:\[\text{Average Rate of Change} = \frac{f(x_2) - f(x_1)}{x_2 - x_1}\]
  • Determine \(f(x_1)\) and \(f(x_2)\) by evaluating the function at the given x-values.
  • Subtract these function values to find the change in output.
  • Divide this difference by the change in x-values \((x_2 - x_1)\).
This formula provides insight into the rate at which the function's value increases or decreases over a specific interval. It is especially useful in understanding behavior over segments of quadratic functions.

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