Chapter 3: Problem 50
Find an equation of each line described. Write each equation in slope- intercept form when possible. Through \((1,-5),\) parallel to the \(y\) -axis
Short Answer
Expert verified
The equation is x = 1.
Step by step solution
01
Understand the Problem
We're asked to find the equation of a line that goes through a specific point \(1, -5\) and is parallel to the y-axis. A line parallel to the y-axis is a vertical line.
02
Identify the Characteristics of the Line
A vertical line has the equation form \(x = a\), where \(a\) is the x-coordinate of any point on the line. Vertical lines do not fit the slope-intercept form \(y = mx + b\), because their slope is undefined.
03
Determine the Equation
Since the line is vertical and passes through the point \(1, -5\), it will intersect the x-axis at \(x = 1\). Thus, the equation of the line is simply \(x = 1\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Vertical Line
A vertical line is quite unique in the world of mathematics. Unlike most lines that might tilt left or right, a vertical line runs straight up and down the graph. The defining characteristic of a vertical line is that all points on the line have the same x-coordinate. For example, if a vertical line passes through the point (1, -5), it means every point along this line has an x-coordinate of 1. Here's a simple rundown of vertical lines:
- The equation is in the form \(x = a\), where \(a\) is the x-coordinate.
- Vertical lines have an undefined slope because you cannot divide by zero. If you try to calculate the slope between any two points on a vertical line, you'll end up dividing by zero, which is mathematically impossible.
- Vertical lines never cross the y-axis, so they do not have a y-intercept.
Slope-Intercept Form
The slope-intercept form is one of the most commonly used ways of writing the equation of a straight line. This form helps you easily identify key features of a line, namely its slope and y-intercept. The standard form for this equation is: \[y = mx + b\] In this form:
- \(m\) represents the slope of the line. The slope indicates how steep the line is and tells you how much \(y\) changes for a unit increase in \(x\).
- \(b\) is the y-intercept. This is where the line crosses the y-axis, meaning it's the value of \(y\) when \(x = 0\).
Equation of a Line
Finding the equation of a line is all about determining a formula that represents all the points on the line. The process varies slightly depending on whether the line is vertical, horizontal, or neither. Let's break it down a bit:
- Vertical Lines: If a line is vertical, its equation is \(x = a\), where \(a\) is the constant x-coordinate for the line. Since vertical lines don't "run" from left to right, they don't have a slope you can calculate.
- Horizontal Lines: These slip easily into the slope-intercept form as \(y = b\), where \(b\) is the constant y-coordinate. The slope of a horizontal line is zero because the line is perfectly flat.
- Other Lines: Besides vertical and horizontal lines, we use the slope-intercept form \(y = mx + b\) for most lines. This helps you quickly identify the slope and y-intercept for easy graphing.