Chapter 3: Problem 35
Use the intercept method to graph each equation. $$ 30 x+y=-30 $$
Short Answer
Expert verified
The x-intercept is \((-1,0)\) and the y-intercept is \((0,-30)\). Graph these points and draw the line through them.
Step by step solution
01
Identify the Equation Format
The given equation is \(30x + y = -30\). This is a linear equation in standard form \(Ax + By = C\), where \(A = 30\), \(B = 1\), and \(C = -30\).
02
Find the X-Intercept
To find the x-intercept, set \(y = 0\) in the equation and solve for \(x\): \(30x + 0 = -30\). This simplifies to \(30x = -30\). Dividing both sides by 30 gives \(x = -1\). The x-intercept is \((-1, 0)\).
03
Find the Y-Intercept
To find the y-intercept, set \(x = 0\) in the equation and solve for \(y\): \(30(0) + y = -30\). This simplifies to \(y = -30\), so the y-intercept is \((0, -30)\).
04
Graph the Intercepts
Plot the x-intercept \((-1, 0)\) and the y-intercept \((0, -30)\) on a coordinate plane. These two points will determine the line.
05
Draw the Line
Draw a straight line through the plotted intercepts. This line represents the equation \(30x + y = -30\). Ensure it extends across the entire graph, showing the infinite nature of the line.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Linear Equations
A linear equation is a type of equation that forms a straight line when graphed on a coordinate plane. It can usually be written in the form \(Ax + By = C\), where \(A\), \(B\), and \(C\) are constants. In this format, \(x\) and \(y\) are variables that represent points on a graph.
Linear equations have many properties:
Linear equations have many properties:
- They create straight lines when plotted.
- Their solutions are the sets of all points \( (x, y) \) that lie on the line.
- They can have infinitely many solutions, as the line extends indefinitely in both directions.
- You can graph them using points like intercepts, which are locations where the line crosses the axes.
X-Intercept
The x-intercept is a key feature of any graphed line. It refers to the point at which the line crosses the x-axis on a graph.
To find this intercept, you simply set the \(y\) variable to zero in the equation and solve for \(x\):
To find this intercept, you simply set the \(y\) variable to zero in the equation and solve for \(x\):
- This method effectively "removes" y from the equation because, at the x-intercept, \(y = 0\).
- For instance, with the equation \(30x + y = -30\), setting \(y = 0\) leads us to \(30x = -30\), so \(x = -1\). Thus, the x-intercept is \((-1, 0)\).
Y-Intercept
The y-intercept is another foundational aspect when working with linear equations. It is the point where the line crosses the y-axis, and happens when \(x = 0\).
To locate the y-intercept, you substitute \(x = 0\) into the equation:
To locate the y-intercept, you substitute \(x = 0\) into the equation:
- By making \(x\) zero, you focus on what happens purely along the y-axis.
- Using the example equation \(30x + y = -30\), substituting \(x = 0\) gives \(y = -30\), thus the y-intercept is \((0, -30)\).
Graphing
Graphing is the process of representing algebraic equations visually on a coordinate plane. This step is particularly beneficial for understanding the relationship and interaction between variables.
To graph a linear equation using intercepts:
To graph a linear equation using intercepts:
- First, you find the x-intercept by setting \(y = 0\).
- Then, determine the y-intercept by setting \(x = 0\).
- Once both intercepts, \((-1, 0)\) and \((0, -30)\) for our example, are found, you plot them on the graph.
- With these two plotted points, you draw a straight line through them.