Chapter 1: Problem 7
Write the \(y\)-axis as a line in \(\mathbb{R}^{2}\).
Short Answer
Expert verified
The y-axis in \( \mathbb{R}^{2} \) can be represented as \(x=0\)
Step by step solution
01
Understanding the y-axis
In \( \mathbb{R}^{2} \), the y-axis is defined as the vertical line that passes through the point (0,0). On this line, the x-coordinate of every point is 0, while the y-coordinate varies.
02
Writing the equation
In a two-dimensional Cartesian coordinate system, a straight line can be represented by the general equation \(y = mx + c\), where \(m\) denotes the slope of the line and \(c\) is the y-intercept. The y-axis has a slope of 0 (as it's a vertical line), and it passes through the origin, so its y-intercept \(c\) is also 0.
03
Final equation for y-axis
Given the slope and y-intercept, the equation for y-axis becomes \(y = 0*x + 0\). Since multiplying any number by 0 yields 0, the equation simplifies to \(0 = 0\), which stands for all \(y\) in \(\mathbb{R}\). So the simplest form to present y-axis is \(x=0\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Cartesian Coordinate System
The Cartesian coordinate system is a foundational tool in mathematics, particularly in geometry and algebra. It is a two-dimensional system for graphing points, lines, and curves, consisting of two perpendicular axes: the x-axis (horizontal) and the y-axis (vertical). Every point in the coordinate plane can be specified by an ordered pair of numbers (x, y), known as coordinates. The x-coordinate indicates a point's horizontal position, while the y-coordinate indicates its vertical position.
When looking at a textbook exercise such as writing the y-axis as a line in the Cartesian coordinate system, it's essential to visualize the y-axis as one of the two reference lines that determine the grid of the plane. Since all points on the y-axis have an x-coordinate of zero, we can represent the y-axis as the line where x is always zero, regardless of the value of y.
When looking at a textbook exercise such as writing the y-axis as a line in the Cartesian coordinate system, it's essential to visualize the y-axis as one of the two reference lines that determine the grid of the plane. Since all points on the y-axis have an x-coordinate of zero, we can represent the y-axis as the line where x is always zero, regardless of the value of y.
Linear Equations
Linear equations form the backbone of algebra and are one of the simplest types of equations in mathematics. They describe a straight line in the geometric Cartesian coordinate system. A linear equation in two variables, x and y, can be written in the form \( y = mx + b \), where 'm' represents the slope of the line, and 'b' is the y-intercept, the point where the line crosses the y-axis.
For the y-axis, which is a vertical line, we approach it slightly differently as it doesn't have a 'slope' that we typically define for non-vertical lines. Instead, the equation that represents the y-axis can be seen as a special case of a linear equation where x is always zero, leading to the equation \( x = 0 \), reflecting the idea that no matter what y-value we have, x remains constant at zero. Understanding linear equations helps us to represent and solve real-world problems involving constant rates of change and proportional relationships.
For the y-axis, which is a vertical line, we approach it slightly differently as it doesn't have a 'slope' that we typically define for non-vertical lines. Instead, the equation that represents the y-axis can be seen as a special case of a linear equation where x is always zero, leading to the equation \( x = 0 \), reflecting the idea that no matter what y-value we have, x remains constant at zero. Understanding linear equations helps us to represent and solve real-world problems involving constant rates of change and proportional relationships.
Slope-Intercept Form
The slope-intercept form is pivotal for graphing linear equations quickly and effectively. It is expressed as \( y = mx + b \) where 'm' is the slope of the line, and 'b' is the y-intercept. The slope 'm' is a measure of the steepness or inclination of the line, indicating how much y increases for a one-unit increase in x. In contrast, 'b' represents the point at which the line crosses the y-axis, thereby indicating the height at which the line 'intercepts' the axis.
Concerning the exercise provided, for the y-axis, the slope, in this case, is undefined because the y-axis is a vertical line. Nevertheless, in slope-intercept form, we consider the y-axis to be a line with a slope of zero and a y-intercept of zero. However, this simplifies to the equation \( x = 0 \), since the vertical y-axis has an undefined slope and can't be represented by a traditional slope-intercept equation.
Concerning the exercise provided, for the y-axis, the slope, in this case, is undefined because the y-axis is a vertical line. Nevertheless, in slope-intercept form, we consider the y-axis to be a line with a slope of zero and a y-intercept of zero. However, this simplifies to the equation \( x = 0 \), since the vertical y-axis has an undefined slope and can't be represented by a traditional slope-intercept equation.