Chapter 5: Problem 26
For the following exercises, find the intercepts of the functions. $$ g(n)=-2(3 n-1)(2 n+1) $$
Short Answer
Expert verified
X-intercepts: \( n = \frac{1}{3}, -\frac{1}{2} \); Y-intercept: \( g(n) = 2 \).
Step by step solution
01
Understand the Problem
We need to find the intercepts of the function \( g(n) = -2(3n - 1)(2n + 1) \). The intercepts are the points where the graph of the function crosses the axes.
02
Find the X-Intercepts
To find the x-intercepts, set \( g(n) = 0 \) and solve for \( n \). That gives us \(-2(3n - 1)(2n + 1) = 0\). Since \(-2\) is nonzero, we can ignore it. We are left with solving two equations:1. \(3n - 1 = 0\)2. \(2n + 1 = 0\)Solving these gives the x-intercepts.
03
Solve 3n - 1 = 0
Add 1 to both sides of the equation:\[3n = 1\]Then divide by 3:\[n = \frac{1}{3}\]
04
Solve 2n + 1 = 0
Subtract 1 from both sides of the equation:\[2n = -1\]Then divide by 2:\[n = -\frac{1}{2}\]
05
Find the Y-Intercept
To find the y-intercept, set \( n = 0 \) and calculate \( g(n) \):\[g(0) = -2(3(0) - 1)(2(0) + 1) = -2(-1)(1) = 2\] This gives the y-intercept.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
X-Intercepts
The x-intercepts of a function are where the graph crosses the x-axis. This means the value of the function is zero at these points. To find them for the function \( g(n) = -2(3n - 1)(2n + 1) \), set the entire expression to zero: \[ -2(3n - 1)(2n + 1) = 0 \] Here, you can ignore the \(-2\) because it won't affect the equation being zero.
- First, solve \( 3n - 1 = 0 \). Add 1 to both sides, giving \( 3n = 1 \). Then divide by 3: \( n = \frac{1}{3} \).
- Next, solve \( 2n + 1 = 0 \). Subtract 1 from both sides, giving \( 2n = -1 \). Then divide by 2: \( n = -\frac{1}{2} \).
Y-Intercept
The y-intercept of a function is where the graph crosses the y-axis. This happens when the input, or \( n \), is zero. For \( g(n) = -2(3n - 1)(2n + 1) \), find the y-intercept by plugging \( n = 0 \) into the function: \[ g(0) = -2(3(0) - 1)(2(0) + 1) \] Simplify the expression:
- \( 3(0) - 1 = -1 \)
- \( 2(0) + 1 = 1 \)
- Then, calculate \( -2(-1)(1) = 2 \)
Solving Equations
An essential part of finding intercepts is solving equations. When the function is set to zero to find x-intercepts or when specific values are substituted to find a y-intercept, equation-solving skills are key. There are different types of equations you might encounter:
- Linear equations like \( 3n - 1 = 0 \) or \( 2n + 1 = 0 \), which are solved by isolating \( n \).
- Isolating terms involving \( n \)
- Simplifying using basic arithmetic operations (addition, subtraction, multiplication, division)
Graph of the Function
Understanding the graph of a function is crucial in visualizing intercepts. The x-intercepts \( n = \frac{1}{3} \) and \( n = -\frac{1}{2} \) indicate points where the graph will touch or cross the x-axis. Meanwhile, the y-intercept shows where the graph crosses the y-axis, which for our function is at (0, 2). Graphically:
- X-intercepts are points on the x-axis, visually identifiable as zero values in the function output.
- The y-intercept is where the curve or line crosses the y-axis.