Chapter 2: Problem 19
Find an equation of the line that satisfies the given conditions. Through \((2,1)\) and \((1,6)\)
Short Answer
Expert verified
The equation of the line is \( y = -5x + 11 \).
Step by step solution
01
Calculate Slope
To find the slope (m) of the line, we use the slope formula: \( m = \frac{y_2 - y_1}{x_2 - x_1} \). Plugging in the given points \((x_1, y_1) = (2, 1)\) and \((x_2, y_2) = (1, 6)\), we get: \( m = \frac{6 - 1}{1 - 2} = \frac{5}{-1} = -5 \). Thus, the slope is \( -5 \).
02
Use Point-Slope Form
The point-slope formula of a line is \( y - y_1 = m(x - x_1) \). Using the slope \( m = -5 \) and the point \((2, 1)\), substitute into the formula: \( y - 1 = -5(x - 2) \).
03
Simplify to Slope-Intercept Form
To convert the equation to slope-intercept form \( y = mx + b \), distribute and simplify: \( y - 1 = -5x + 10 \). Adding 1 to both sides gives \( y = -5x + 11 \).
04
Verify with Second Point
Ensure the equation passes through the second point \((1, 6)\). Substitute \( x = 1 \) into the equation: \( y = -5(1) + 11 = -5 + 11 = 6 \). This confirms the equation works.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope
The slope of a line is a measure that indicates how steep the line is. You calculate the slope by dividing the change in the y-values by the change in the x-values between two points on the line. This is often described as "rise over run."
To find the slope of a line given two points, you can use the formula \[m = \frac{y_2 - y_1}{x_2 - x_1}.\]
You just substitute the coordinates of the points into this formula.
To find the slope of a line given two points, you can use the formula \[m = \frac{y_2 - y_1}{x_2 - x_1}.\]
You just substitute the coordinates of the points into this formula.
- In our exercise, we calculated the slope between the points \((2, 1)\) and \((1, 6)\).
- Using the formula, the calculation is \(-5 = \frac{6 - 1}{1 - 2}\).
- A negative result means the line decreases from left to right, whereas a positive slope indicates an upward trend.
Point-Slope Form
The point-slope form of a line’s equation is useful because it allows you to write the equation of a line if you know one point on the line and its slope. The form is \[y - y_1 = m(x - x_1)\],where \(m\)is the slope, and \(x_1, y_1\) is a point on the line.
In the given exercise:
In the given exercise:
- We used the slope \(m = -5\)and the point \((2, 1)\).
- Substituting these into the equation, we obtain \(y - 1 = -5(x - 2).\)
Slope-Intercept Form
The slope-intercept form of a line's equation is a way to express the line in an easily interpretable form. This equation format is \[y = mx + b\],where \(m\) is the slope and \(b\) is the y-intercept, the point where the line crosses the y-axis. This form is practical because it immediately reveals the slope and y-intercept.
To convert the point-slope form into the slope-intercept form in our exercise:
To convert the point-slope form into the slope-intercept form in our exercise:
- We started with \(y - 1 = -5(x - 2)\),expanded it to \(y = -5x + 11\).