Chapter 5: Problem 47
Find the \(x\) - and \(y\) -intercepts of the line with the given equation. Sketch the line using the intercepts. A calculator can be used to check the graph. $$12 x+y=30$$
Short Answer
Expert verified
The x-intercept is \(\frac{5}{2}\) and the y-intercept is 30.
Step by step solution
01
Find the x-intercept
To find the x-intercept, set the value of \(y\) to 0 in the equation and solve for \(x\):\[12x + 0 = 30\]\[12x = 30\]Divide both sides by 12 to solve for \(x\):\[x = \frac{30}{12} = \frac{5}{2}\]So, the x-intercept is at \(\left(\frac{5}{2}, 0\right)\).
02
Find the y-intercept
To find the y-intercept, set the value of \(x\) to 0 in the equation and solve for \(y\):\[12(0) + y = 30\]\[y = 30\]So, the y-intercept is at \((0, 30)\).
03
Sketch the line using intercepts
Plot the x-intercept \(\left(\frac{5}{2}, 0\right)\) on the x-axis and the y-intercept \((0, 30)\) on the y-axis on a coordinate grid. Draw a straight line through these two points to represent the equation \(12x + y = 30\).
04
Verify the graph with a calculator
Using a graphing calculator, input the equation \(y = -12x + 30\) (rearrange to solve for \(y\)) to check that the graph passes through the points \(\left(\frac{5}{2}, 0\right)\) and \((0, 30)\), verifying the accuracy of our sketch.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Intercepts
The intercepts of a line are the points where the line crosses the x-axis and y-axis. Determining the intercepts is a foundational skill in understanding linear equations. Here's how you find these important points:
- The x-intercept occurs where the line crosses the x-axis. At this point, the value of y is zero. To find it, set \(y = 0\) in the equation and solve for \(x\). For the equation \(12x + y = 30\), setting \(y = 0\) gives \(12x = 30\). Solving, we find the x-intercept at \(x = \frac{5}{2}\), or \((\frac{5}{2}, 0)\).
- The y-intercept occurs where the line crosses the y-axis. At this point, the value of x is zero. To find it, set \(x = 0\) and solve for \(y\). For the same equation, \(12(0) + y = 30\), results in \(y = 30\). Thus, the y-intercept is \((0, 30)\).
Graphing Lines
To draw the line represented by a linear equation, you can start by identifying the intercepts. In our case, the line with the equation \(12x + y = 30\) can be sketched through these simple steps:Firstly, plot the intercepts:
- Mark the x-intercept \((\frac{5}{2}, 0)\) on the x-axis.
- Mark the y-intercept \((0, 30)\) on the y-axis.
- Draw a straight line through both intercepts. This line is the graphical representation of the equation.
- Extend the line in both directions beyond the intercepts, maintaining its straight nature, to represent the line across the coordinate plane.
Coordinate Plane Visualization
The coordinate plane is a two-dimensional surface on which we can plot points, lines, and curves. Here's a simple guide to visualizing linear equations on it:Understanding the layout:
- The horizontal line is the x-axis and the vertical line is the y-axis. Their intersection is the origin, \((0, 0)\).
- Points are represented by ordered pairs \((x, y)\), where \(x\) is the position along the horizontal axis and \(y\) is the position along the vertical axis.
- Plotting intercepts helps anchor the line. The x-intercept and y-intercept show exactly where the line will touch the axes.
- After plotting, drawing the line gives a complete visual of the linear equation, making abstract numbers tangible and easier to analyze.
- Checking the line with a graphing calculator reinforces understanding, as many graph calculative tools allow visual overlays on the coordinate plane.