Chapter 1: Problem 167
Find the average rate of change of each function on the interval specified for real numbers \(b\) or \(h.\) \(r(t)=4 t^{3}\) on \([2,2+h]\)
Short Answer
Expert verified
The average rate of change is \(48 + 24h + 4h^2\).
Step by step solution
01
Understand the Average Rate of Change Formula
The average rate of change of a function between two points is given by the formula \( \frac{f(b) - f(a)}{b - a} \). Here, \( b \) and \( a \) are the two points over an interval. For function \( r(t) = 4t^3 \), we need to calculate it over the interval \([2, 2+h]\). So, we identify \( a = 2 \) and \( b = 2+h \).
02
Calculate Function Values
Evaluate \( r(t) = 4t^3 \) at the endpoints of the interval:- At \( t = 2 \), \( r(2) = 4(2)^3 = 4 \times 8 = 32 \).- At \( t = 2+h \), \( r(2+h) = 4(2+h)^3 \).
03
Expand the Expression for \(r(2+h)\)
First, expand \( (2+h)^3 \):\( (2+h)^3 = (2+h)(2+h)(2+h) = 8 + 12h + 6h^2 + h^3 \).Thus, \( r(2+h) = 4(8 + 12h + 6h^2 + h^3) = 32 + 48h + 24h^2 + 4h^3 \).
04
Compute the Difference \(r(b) - r(a)\)
We subtract \( r(2) \) from \( r(2+h) \):\( r(2+h) - r(2) = (32 + 48h + 24h^2 + 4h^3) - 32 = 48h + 24h^2 + 4h^3 \).
05
Apply the Average Rate of Change Formula
Use the average rate of change formula:\[ \text{Average rate of change} = \frac{r(2+h) - r(2)}{(2+h) - 2} = \frac{48h + 24h^2 + 4h^3}{h} \].Simplifying, divide each term by \( h \):\[ = 48 + 24h + 4h^2 \].
06
Conclusion
The average rate of change of the function \( r(t)=4t^3 \) on the interval \([2, 2+h]\) is expressed as a function of \( h \):\( 48 + 24h + 4h^2 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding Polynomials
A polynomial is a mathematical expression consisting of variables and coefficients, constructed using only addition, subtraction, multiplication, and non-negative integer exponents of variables. In this example, we deal with a function given by a polynomial:
- The function is given as: \( r(t) = 4t^3 \).
- This is a cubic polynomial because the highest power of the variable \( t \) is 3.
- Polynomials are fundamental in algebra and serve as a base for more complex calculations.
Explaining Interval Notation
Interval notation is a way of describing the range of values on which a function is evaluated. In our exercise, the interval is given as
- \([2, 2+h]\), where 2 is a prescriptive start value, and \(2 + h\) suggests a flexible endpoint.
- The square brackets \([ ]\) indicate that both endpoints are included in the interval.
Delving into Function Evaluation
Function evaluation involves calculating the output of a function for specific input values. For the function \( r(t) = 4t^3 \), the evaluations occur at the boundaries of the interval:
- At \( t = 2 \), evaluate the function: \( r(2) = 4(2)^3 = 32 \).
- At \( t = 2+h \), the value is \( r(2+h) = 4(2+h)^3 \).
Mastering Expansion and Simplification
Expansion and simplification are vital techniques in algebra, essential for solving polynomial equations. In our problem, we expand the expression \((2+h)^3\):
- Multiply the binomial step by step to obtain: \( (2+h)^3 = 8 + 12h + 6h^2 + h^3 \).
- Next, scale by 4 to get \( r(2+h) = 32 + 48h + 24h^2 + 4h^3 \).