Chapter 2: Problem 68
You are given a line and a point which is not on that line. Find the line perpendicular to the given line which passes through the given point. . \(y=\frac{4-x}{3}, P(1,-1)\)
Short Answer
Expert verified
The equation of the line perpendicular to \(y = \frac{4-x}{3}\) passing through \(P(1,-1)\) is \(y = 3x - 4\).
Step by step solution
01
Identify the Slope of the Given Line
The given line equation is \(y = \frac{4-x}{3}\). Rewriting it in the slope-intercept form \(y = mx + b\), we get \(y = -\frac{1}{3}x + \frac{4}{3}\). Thus, the slope \(m\) of the given line is \(-\frac{1}{3}\).
02
Find the Perpendicular Slope
The slope of a line perpendicular to another is the negative reciprocal of the original slope. The given line's slope is \(-\frac{1}{3}\), so the perpendicular slope is \(3\) (i.e., the negative reciprocal is \( \frac{1}{-\left(-\frac{1}{3}\right)} = 3\)).
03
Use Point-Slope Form to Write the Equation
We use the point-slope form \(y - y_1 = m(x - x_1)\), with the point \((1,-1)\) and the perpendicular slope \(3\). Substitute into the formula: \(y - (-1) = 3(x - 1)\).
04
Simplify the Equation
Simplify the equation from step 3: \(y + 1 = 3x - 3\). Solving for \(y\), subtract \(1\) from both sides to find the intercept form: \(y = 3x - 4\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope-Intercept Form
The slope-intercept form of a line is an equation that helps us understand the linear relationship between two variables, usually the coordinates on a graph. The formula for this form is written as \( y = mx + b \), where:
- \( y \) represents the dependent variable.
- \( m \) is the slope of the line.
- \( x \) is the independent variable.
- \( b \) is the y-intercept, or the point where the line crosses the y-axis.
Negative Reciprocal
When two lines are perpendicular, their slopes are related by the concept of a negative reciprocal. If the slope of one line is \( m \), the slope of a line perpendicular to it will be \(-\frac{1}{m}\).
- This means you flip the fraction (reciprocal) and change the sign (negative).
- For example, for a slope \( m = -\frac{1}{3} \), the perpendicular slope will be \( 3 \).
Point-Slope Form
The point-slope form of a line equation can be a handy tool when you know a point on the line and its slope. It is represented as \( y - y_1 = m(x - x_1) \), where:
- \( (x_1, y_1) \) are the coordinates of a known point on the line.
- \( m \) is the slope of the line.
Equation of a Line
Understanding how to derive the equation of a line is essential in algebra and geometry. This can be done using either the slope-intercept form or the point-slope form, depending on the information you have.
- The slope-intercept form \( y = mx + b \) requires knowing the y-intercept, whereas the point-slope form \( y - y_1 = m(x - x_1) \) needs at least one point on the line and its slope.