Chapter 3: Problem 71
Find \(k\) so that the line through \((2, k)\) and \((-3,-5)\) has slope \(\frac{1}{2}\)
Short Answer
Expert verified
The value of \( k \) is \( -\frac{5}{2} \).
Step by step solution
01
Understand the slope formula
The slope of a line through two points \((x_1, y_1)\) and \((x_2, y_2)\) is calculated using the formula \( m = \frac{y_2 - y_1}{x_2 - x_1} \).
02
Plug in given points and slope
Substitute the given points \( (2, k) \) and \((-3, -5)\) into the slope formula, along with the given slope \( \frac{1}{2} \). \(\frac{-5 - k}{-3 - 2} = \frac{1}{2} \).
03
Simplify the formula
Simplify the denominator: \( -3 - 2 = -5 \). This gives the equation: \(\frac{-5 - k}{-5} = \frac{1}{2} \).
04
Solve for k
To clear the fraction, multiply both sides by \( -5 \): \((-5 - k) = \frac{1}{2} \times -5\) Simplify: \(-5 - k = -\frac{5}{2} \). Next, add 5 to both sides: \(- k = -\frac{5}{2} + 5 \). Finally, simplify to find \( k \): \(- k = -\frac{5}{2} + \frac{10}{2}\ = \frac{5}{2}\) Divide by -1 to solve for \( k \): \( k = -\frac{5}{2} \).
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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 way to measure the steepness and direction of a line. It tells us how much the y-coordinate (or vertical position) of a point on the line changes for every single unit of change in the x-coordinate (or horizontal position). This is why it's represented as 'rise over run'. You can calculate the slope between two points \( (x_1, y_1) \) and \( (x_2, y_2) \) using the formula: \[ m = \frac{y_2 - y_1}{x_2 - x_1} \].
Here:
Here:
- \(m\) is the slope
- \(x_1\), \(y_1\) are the coordinates of the first point
- \(x_2\), \(y_2\) are the coordinates of the second point
- If the slope is positive, the line goes upwards as you move to the right.
- If the slope is negative, the line goes downwards as you move to the right.
- If the slope is zero, the line is horizontal.
- If the slope is undefined (division by zero), the line is vertical.
linear equations
Linear equations are equations of the first degree, meaning they have no exponents greater than 1. A typical linear equation looks like this: \[ y = mx + c \] Here:
- \( y \) is the dependent variable.
- \( x \) is the independent variable.
- \( m \) is the slope.
- \( c \) is the y-intercept, the point where the line crosses the y-axis.
coordinate geometry
Coordinate geometry, also called analytic geometry, is a branch of mathematics that uses algebra to study geometric problems. It involves the coordinate plane which is formed by two perpendicular number lines: the x-axis (horizontal) and the y-axis (vertical). Every point on this plane is defined by a pair of coordinates \( (x, y) \). Key concepts in coordinate geometry include:
- The distance formula: used to calculate the distance between two points.
- The midpoint formula: used to find the midpoint of a segment connecting two points.
- The slope formula: as explained earlier, used to measure the steepness of a line connecting two points.