Chapter 5: Problem 44
Solve the given problems. Find the value of \(k\) such that the line through \((0, k)\) and \((-k,-1)\) has a slope of \(1 / 2\).
Short Answer
Expert verified
The value of \(k\) is \(-2\).
Step by step solution
01
Understand the Slope Formula
The formula for the slope \( m \) of a line through two points \((x_1, y_1)\) and \((x_2, y_2)\) is given by: \[ m = \frac{y_2 - y_1}{x_2 - x_1} \] Since the slope is given as \( \frac{1}{2} \), we can equate this to the formula of the slope for the line through points \((0, k)\) and \((-k, -1)\).
02
Apply the Slope Formula
Insert the coordinates into the slope formula, where \( (x_1, y_1) = (0, k) \) and \( (x_2, y_2) = (-k, -1) \): \[ \frac{-1 - k}{-k - 0} = \frac{1}{2} \] Simplify the expression: \[ \frac{-1 - k}{-k} = \frac{1}{2} \]
03
Simplify the Slope Equation
The equation can be simplified: \[ \frac{-1 - k}{-k} = \frac{1}{2} \] Multiply both sides by \(-k\) to clear the fraction: \[ -1 - k = \frac{1}{2}(-k) \] This simplifies to: \[ -1 - k = -\frac{k}{2} \]
04
Solve for \(k\)
To eliminate the negative signs and fractions, multiply the entire equation by \(-2\): \[ 2(1 + k) = k \] Simplify and solve this equation: \[ 2 + 2k = k \] \[ 2k - k = -2 \] \[ k = -2 \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope Formula
The slope formula is a fundamental concept in calculus and coordinate geometry, used to determine the steepness of a line. It describes how the y-value of a line change as the x-value increases. The formula for the slope, represented as \( m \), between two points \((x_1, y_1)\) and \((x_2, y_2)\) is:
\[m = \frac{y_2 - y_1}{x_2 - x_1}\]
This formula calculates the ratio of the vertical change (\( y_2 - y_1 \)) to the horizontal change (\( x_2 - x_1 \)) between two points. A positive slope indicates that the line is rising as it moves from left to right, while a negative slope indicates it is falling.
\[m = \frac{y_2 - y_1}{x_2 - x_1}\]
This formula calculates the ratio of the vertical change (\( y_2 - y_1 \)) to the horizontal change (\( x_2 - x_1 \)) between two points. A positive slope indicates that the line is rising as it moves from left to right, while a negative slope indicates it is falling.
- If the slope is zero, the line is horizontal.
- An undefined slope indicates a vertical line.
- In our problem, the slope is given as \( \frac{1}{2} \), meaning for every 2 units moved horizontally, there is a 1 unit increase vertically.
Linear Equations
Linear equations are equations that create a straight line when plotted on a graph. They are fundamental in algebra and calculus. The general form of a linear equation in two variables is:
\[y = mx + b\]
Here, \( m \) is the slope, and \( b \) is the y-intercept, the point where the line crosses the y-axis. Linear equations can be derived from the slope formula by rearranging terms to fit this form, allowing us to easily visualize the relationship between variables.
\[y = mx + b\]
Here, \( m \) is the slope, and \( b \) is the y-intercept, the point where the line crosses the y-axis. Linear equations can be derived from the slope formula by rearranging terms to fit this form, allowing us to easily visualize the relationship between variables.
- In our exercise, we used points to determine the equation of the line by employing the slope formula.
- Subsequently, we solved for \( k \) ensuring the slope between the points matches the given value, \( \frac{1}{2} \).
Coordinate Geometry
Coordinate geometry, also known as analytic geometry, combines algebra and geometry to understand shapes and their properties through a coordinate system. By using the Cartesian plane, we can describe points, lines, and curves algebraically.
In our case:
In our case:
- We identified points \((0, k)\) and \((-k, -1)\) on the Cartesian plane.
- Using these coordinates alongside the slope formula enabled us to express geometric relationships in precise algebraic terms.