Question

Find the slope and \(y\) intercept of each straight line and make a graph. $$y=7 x+2$$

Short answer

The slope of the line is 7, and the y-intercept is the point (0,2). To graph the line, plot the y-intercept and use the slope to find another point, then draw a straight line through these points.

Step-by-step solution

Identify Slope and Y-Intercept from Equation

From the equation of the straight line in slope-intercept form, which is given by the formula \(y=mx+b\), identify the slope (\(m\)) and the y-intercept (\(b\)). For the given equation \(y=7x+2\), the slope \(m\) is 7 and the y-intercept \(b\) is 2.

Plot the Y-Intercept on the Graph

Begin graphing the equation by plotting the point where the line crosses the y-axis, which is the y-intercept (0,2). This is the starting point for drawing the line.

Use the Slope to Find Another Point

Using the slope of 7, which means rise over run or a change in y for a change in x, plot a second point starting from the y-intercept (0,2). Move up 7 units in the y direction and 1 unit to the right to place the second point at (1,9).

Draw the Line

Draw a straight line through the two points, extending the line across the graph. This visually represents the equation \(y=7x+2\).

Key concepts

Understanding the Slope of a Line

When we talk about the slope of a line, we refer to a number that describes both the direction and steepness of the line. Typically denoted by the letter 'm', it is a crucial part of the equation for a line in slope-intercept form, which looks like this: \(y = mx + b\).

In the context of the given exercise, the slope is 7, extracted from the equation \(y = 7x + 2\). This number tells us that for every unit you move to the right along the x-axis, the line goes up by 7 units. It's a bit like climbing a hill: the larger the slope, the steeper your ascent. If the slope were a negative number, that would indicate a descent. The concept of 'rise over run' is central to understanding slope, where 'rise' refers to the vertical change and 'run' refers to the horizontal change between points on the line.

To ensure this is easy to grasp, picture walking along a flat road (a slope of 0, where the road doesn't go up or down) versus hiking up a steep mountain trail (a large positive slope) or descending into a valley (a negative slope).

Decoding the Y-Intercept

The y-intercept is the point where a line crosses the y-axis of a coordinate plane. In slope-intercept form, \(y = mx + b\), the y-intercept is represented by the 'b' value. For the equation provided in the exercise, \(y = 7x + 2\), the y-intercept is 2. This means the line will cross the y-axis at the point (0,2).

Imagine the y-axis as a vertical line where all points have an x-coordinate of 0. So, when we're looking for the y-intercept, we're essentially asking ourselves: 'Where does the line touch this vertical line?' The answer lies in the equation—it's at the value of 'b'.

In practical scenarios, the y-intercept could represent a starting value or initial condition before any changes occur. For instance, if the line represents a savings account balance over time, the y-intercept might be the initial deposit before any interest is accumulated.

Graphing Linear Equations Step by Step

Graphing linear equations involves drawing a line that represents all possible solutions to the equation. The process is straightforward with the slope-intercept form of a linear equation, \(y = mx + b\).

To graph the equation such as \(y = 7x + 2\), we first plot the y-intercept (0,2) on the graph. This is the point where the line meets the y-axis. Next, we use the slope to determine another point. With a slope of 7, we move up 7 units (the rise) for every 1 unit we move to the right (the run), which gives us the point (1,9).

Now that we have two points, the line can be drawn through these points, extending it to span the graph. This line visually conveys all the points where the x and y values satisfy the equation. Using a ruler to connect these points will help ensure the line is straight, showcasing the linear relationship between x and y.

Students can improve their understanding of this process by practicing with different equations, noticing how changes in the slope and y-intercept values affect the line's position and angle on the graph.