Question

Write the equation in slope-intercept form. Then graph the equation. $$ x-y=0 $$

Short answer

The equation in slope intercept form is \(y = x\). The graph of the equation will be a straight line passing through the origin, making a 45-degree angle with the x-axis.

Step-by-step solution

Convert to Slope-intercept Form

Starting with the given equation \(x - y = 0\), to convert to slope-intercept form, subtract \(x\) from both sides to isolate \(y\): \(-y = -x\). Now, to make \(y\) positive, multiply both sides of the equation by -1 resulting in \(y = x\). Thus, the equation in slope-intercept form is \(y = x\). Here, \(m = 1\) (the coefficient of \(x\)) and \(b = 0\). This means the line has a slope of 1 and intersects the y-axis at the point (0,0).

Graph the Equation

To graph the equation \(y = x\), start by plotting the y-intercept which is at (0,0). Since the slope is 1 (which is the rise over run), for each unit step to the right in the x direction (run), move one unit up in the y direction (rise). Plot a few more points following this pattern and then join these points to complete the graph. The line should intersect the origin, and form a 45-degree angle with the x-axis (this is because the slope is 1).

Key concepts

Linear Equations

Understanding linear equations is fundamental in algebra. A linear equation is an algebraic equation in which each term is either a constant or the product of a constant and a single variable. Linear equations can be written in various forms, but one of the most important and commonly used is the slope-intercept form, expressed as \( y = mx + b \).

In the equation, \( m \) stands for the slope, which represents the rate at which the \( y \) value changes for every unit increase in the \( x \) value. The \( b \) represents the y-intercept, which is the point where the line crosses the y-axis on a graph. This point has an \( x \)-coordinate of 0. When dealing with linear equations, one of the key skills is to rearrange them into the slope-intercept form because it readily gives you the information needed to graph the line.

Graphing Linear Equations

Graphing linear equations is a visual way of representing the solutions to these equations. To graph a linear equation, one generally uses a Cartesian coordinate system, where one axis represents the \( x \)-values and the other the \( y \)-values. When a linear equation is presented in the slope-intercept form, graphing becomes an easy two-step process:

1. First, plot the y-intercept \( b \) on the y-axis. This is your starting point, where the line will cross the y-axis.
2. Then, from the y-intercept, use the slope \( m \), which is often given as a fraction \( \frac{rise}{run} \), to determine the direction and steepness of the line. 'Rise' refers to the vertical change, and 'run' refers to the horizontal change.

By plotting additional points using the slope and connecting them with a straight line, you graphically represent all the infinite solutions of the given linear equation.

Slope and y-intercept

The slope and y-intercept are two fundamental characteristics of a line in the context of linear equations. The slope, denoted as \( m \), is a measure of the steepness and direction of a line. It is calculated as the change in \( y \) (rise) over the change in \( x \) (run) between two distinct points on the line. If the slope is positive, the line inclines upward as it moves from left to right. Conversely, a negative slope means the line declines. A slope of zero indicates a horizontal line, and undefined slope (division by zero) corresponds to a vertical line.

The y-intercept is the specific point where the line crosses the y-axis and is represented by the \( b \) in the slope-intercept form. This is where the value of \( x \) is zero. In terms of graphing, it is the starting point for plotting the line. Together, the slope and the y-intercept define the position and orientation of a line on a graph. They are crucial in understanding and predicting the behavior of a line, especially in various applications like statistics, physics, and economics.