Chapter 1: Problem 32
Find a linear function \(g\) given \(g\left(-\frac{1}{4}\right)=-6\) and \(g(2)=3 .\) Then find \(g(-3)\)
Short Answer
Expert verified
The linear function is \(g(x) = 4x - 5\). For \(g(-3)\), the value is \(-17\).
Step by step solution
01
- Determine the form of the linear function
A linear function can be written as: \[ g(x) = mx + c \] where \(m\) is the slope and \(c\) is the y-intercept.
02
- Set up the equations from given points
Insert the given points into the equation: \[ g\left(-\frac{1}{4}\right) = -6 \implies m \left(-\frac{1}{4}\right) + c = -6 \] \[ g(2) = 3 \implies 2m + c = 3 \]
03
- Solve for the slope (m)
We have two equations: 1) \( -\frac{1}{4}m + c = -6 \)2) \( 2m + c = 3 \)Subtract the first equation from the second to eliminate \(c\): \[ 2m + c - \left( -\frac{1}{4}m + c \right) = 3 - (-6) \] \[ 2m + \frac{1}{4}m = 9 \] \[ \frac{9}{4}m = 9 \] \[ m = 4 \]
04
- Solve for the y-intercept (c)
Substitute \(m = 4\) back into one of the original equations. Using \(2m + c = 3\): \[ 2(4) + c = 3 \] \[ 8 + c = 3 \] \[ c = 3 - 8 \] \[ c = -5 \]
05
- Write the equation of the linear function
Now that we have \(m = 4\) and \(c = -5\), the linear function is: \[ g(x) = 4x - 5 \]
06
- Find g(-3)
Substitute \(x = -3\) into the function: \[ g(-3) = 4(-3) - 5 \] \[ g(-3) = -12 - 5 \] \[ g(-3) = -17 \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
slope-intercept form
The slope-intercept form is a way to write the equation of a straight line. This form is commonly written as:
\[ y = mx + b \]
In this equation, m represents the slope of the line, and b is the y-intercept. The y-intercept is where the line crosses the y-axis.
To use the slope-intercept form, follow these steps:
\[ y = mx + b \]
In this equation, m represents the slope of the line, and b is the y-intercept. The y-intercept is where the line crosses the y-axis.
To use the slope-intercept form, follow these steps:
- Identify the slope (m) of the line. This describes how steep the line is.
- Determine the y-intercept (b), which is the point where the line crosses the y-axis.
solving linear equations
Solving linear equations involves finding the values of variables that satisfy the equation. In a linear equation of the form \[ ax + b = c \], the goal is to isolate the variable x.
- First, rearrange the equation to get all terms containing x on one side and the constant terms on the other.
- Simplify the equation by combining like terms.
- Isolate x by performing inverse operations.
function evaluation
Function evaluation involves finding the value of a function for a given input. This is done by substituting the input value into the function.
For a function f(x), if you want to find f(a) where a is a specific value:
1. Substitute -3 for x: \[ g(-3) = 4(-3) - 5 \]
2. Simplify the expression:
\[ g(-3) = -12 - 5 = -17 \] This means that when x = -3, \[ g(x) = -17 \]. Function evaluation is useful for determining specific values and understanding how changes in inputs affect outputs.
For a function f(x), if you want to find f(a) where a is a specific value:
- Identify the function's equation.
- Replace x with a in the equation.
- Simplify the expression to find the result.
1. Substitute -3 for x: \[ g(-3) = 4(-3) - 5 \]
2. Simplify the expression:
\[ g(-3) = -12 - 5 = -17 \] This means that when x = -3, \[ g(x) = -17 \]. Function evaluation is useful for determining specific values and understanding how changes in inputs affect outputs.