Chapter 4: Problem 35
For the following exercises, given each set of information, find a linear equation satisfying the conditions, if possible. \(x\) intercept at (-2,0) and \(y\) intercept at (0,-3)
Short Answer
Expert verified
The equation is \(y = \frac{-3}{2}x - 3\).
Step by step solution
01
Understand the Intercepts
The problem provides two points: the \(x\)-intercept at \((-2,0)\) and the \(y\)-intercept at \((0,-3)\). The \(x\)-intercept means where the line crosses the x-axis, and the \(y\)-intercept meets the y-axis.
02
Use Intercepts to Determine the Slope
The slope \(m\) of the line can be calculated using the formula \(m = \frac{y_2 - y_1}{x_2 - x_1}\). We use the points \((-2,0)\) and \((0,-3)\). So, \(m = \frac{-3 - 0}{0 + 2} = \frac{-3}{2}\).
03
Write the Equation in Point-Slope Form
Using the point-slope form \(y - y_1 = m(x - x_1)\) with the slope \(m = \frac{-3}{2}\) and one of the points, \(x_1 = 0\) and \(y_1 = -3\), substitute: \[y + 3 = \frac{-3}{2}(x - 0)\].
04
Simplify to Slope-Intercept Form
Simplify the equation from point-slope form to slope-intercept form \(y = mx + b\): \[y + 3 = \frac{-3}{2}x\]. Subtract 3 from both sides to write: \[y = \frac{-3}{2}x - 3\].
05
Verify the Equation
Check that the line satisfies both intercepts. Substitute \(x = -2\) in \(y = \frac{-3}{2}x - 3\) to confirm \(y = 0\), and substitute \(y = -3\) to confirm \(x = 0\). Both verifications are correct.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
X-Intercept
The x-intercept of a line is a foundational concept in linear equations. It represents the point where the line crosses the x-axis. This means the value of y at the x-intercept is always zero.
Understanding x-intercepts is key to graphing and interpreting linear equations. In the equation context from our exercise, the x-intercept is at (-2, 0). At this point, the line meets the x-axis. This tells us a specific detail about the positioning and angle of the line.
Understanding x-intercepts is key to graphing and interpreting linear equations. In the equation context from our exercise, the x-intercept is at (-2, 0). At this point, the line meets the x-axis. This tells us a specific detail about the positioning and angle of the line.
- To find the x-intercept from a linear equation, set y to zero and solve for x.
- Remember, the x-coordinate of the x-intercept does not give the line's slope or steepness, but it does indicate one of the endpoints for slope calculation.
Y-Intercept
The y-intercept is equally important. It is the point where the line crosses the y-axis. At this intercept, the value of x is always zero.
This detail often gives a direct insight into the starting value of a linear pattern when x is initially zero. In our example, the y-intercept is located at (0, -3). This means when the line crosses the y-axis, it does so at y = -3.
This detail often gives a direct insight into the starting value of a linear pattern when x is initially zero. In our example, the y-intercept is located at (0, -3). This means when the line crosses the y-axis, it does so at y = -3.
- To locate the y-intercept from a linear equation like the one in slope-intercept form, simply find the constant term (b).
- This intercept is a crucial reference point for graphing the line.
Point-Slope Form
The point-slope form of a linear equation is a convenient way to write the equation when you know the slope and a single point on the line. This form is: \[y - y_1 = m(x - x_1)\]where \(m\) is the slope and \((x_1, y_1)\) is the known point.
This form is incredibly useful because:
This form is incredibly useful because:
- You can easily create the equation from just one point and the slope.
- It is a stepping stone to other forms, like the slope-intercept form.
Slope Calculation
Calculating the slope of a line is vital in understanding how steeply the line inclines or declines. The slope (\(m\)) is determined using the formula:\[ m = \frac{y_2 - y_1}{x_2 - x_1} \] where \((x_1, y_1)\) and \((x_2, y_2)\) are any two points on the line.
For our problem, using the intercept points \((-2, 0)\) and \((0, -3)\), the slope is \(\frac{-3 - 0}{0 + 2} = \frac{-3}{2}\). This negative slope indicates that our line moves downward as it progresses from left to right.
For our problem, using the intercept points \((-2, 0)\) and \((0, -3)\), the slope is \(\frac{-3 - 0}{0 + 2} = \frac{-3}{2}\). This negative slope indicates that our line moves downward as it progresses from left to right.
- The slope tells us how much y changes for a one-unit change in x.
- A negative slope like ours means the line is decreasing, reflecting in the linear equation as the negative coefficient of x.