Chapter 8: Problem 19
Find an equation of the line with the given slope and containing the given point. Write the equation using function notation. Slope 3 ; through \((1,2)\)
Short Answer
Expert verified
The equation is \( f(x) = 3x - 1 \).
Step by step solution
01
Identify the Slope-Point Form of a Line
To find a line equation with a given slope and point, use the point-slope form: \( y - y_1 = m(x - x_1) \). Here, \( m \) is the slope, and \((x_1, y_1)\) is the point through which the line passes.
02
Substitute the Given Values
Plug the given slope and point into the point-slope formula. The slope \( m \) is 3 and the point is \((1,2)\). Substitute: \( y - 2 = 3(x - 1) \).
03
Simplify the Equation
Distribute the slope 3 on the right-hand side and simplify: \( y - 2 = 3x - 3 \).
04
Solve for y
Add 2 to both sides of the equation to isolate \( y \): \( y = 3x - 1 \).
05
Write in Function Notation
Express the equation in function notation: \( f(x) = 3x - 1 \). This shows that the function \( f \) which outputs \( y \) depends on \( x \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Point-Slope Form
The point-slope form is a convenient way of writing the equation for a line when you know a point on the line and the slope. The point-slope form equation is: \(y - y_1 = m(x - x_1)\), where:
- \(m\) represents the slope of the line.
- \((x_1, y_1)\) is a specific point on the line.
Slope
The slope of a line is a measure of its steepness and direction. In a linear equation, it is denoted by \(m\) and can be calculated using two points from the line: \((x_1, y_1)\) and \((x_2, y_2)\). The formula for slope is: \(m = \frac{y_2 - y_1}{x_2 - x_1}\). Here’s how slope works:
- A positive slope means the line inclines upwards as it moves from left to right.
- A negative slope indicates the line declines downwards.
- A zero slope means the line is horizontal, showing no vertical change.
- An undefined slope signifies a vertical line where the x-values are the same.
Function Notation
Function notation is a way of defining a function in terms of an input-output relationship. It simplifies equations by replacing \(y\) with \(f(x)\), indicating the relationship between \(x\) and its output. Function notation is expressed as \(f(x) = mx + b\), where:
- \(f(x)\) is the output, also known as the dependent variable.
- \(x\) is the input or independent variable.
- \(m\) and \(b\) are constants, where \(m\) is the slope and \(b\) is the y-intercept.
Coordinate Geometry
Coordinate geometry, also known as analytic geometry, involves using algebra to describe and understand geometry. It uses a coordinate system, typically the Cartesian plane, to analyze shapes and solve geometric problems.
- Points on the plane are represented as \((x, y)\) coordinates.
- It helps in defining line equations, such as the one obtained from the point-slope form.
- Slope is a key concept in coordinate geometry, as it is instrumental in understanding line characteristics.