Chapter 1: Problem 36
Write an equation of the line satisfying the following conditions. If possible, write your answer in the form \(y=m x+b\). Slope -1 and passing through the point (4,3)
Short Answer
Expert verified
The equation of the line is \(y = -x + 7\).
Step by step solution
01
Identify the slope-intercept form equation
The slope-intercept form of a linear equation is given by the formula \(y = mx + b\), where \(m\) is the slope and \(b\) is the y-intercept.
02
Use the given slope
We are given the slope \(m = -1\). Substitute \(m = -1\) into the equation. Now the equation is \(y = -x + b\).
03
Substitute the point into the equation
We need to find \(b\), the y-intercept. Use the point \((4, 3)\), meaning \(x = 4\) and \(y = 3\). Substitute these values into the equation \(y = -x + b\): \(3 = -(4) + b\).
04
Solve for b
Simplify the equation: \(3 = -4 + b\). Add 4 to both sides to solve for \(b\): \(3 + 4 = b\). Thus, \(b = 7\).
05
Write the final equation
Substitute \(b = 7\) back into the equation from Step 2. The equation of the line is \(y = -x + 7\).
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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 is a fundamental representation of a linear equation. It is written as \( y = mx + b \), where:
- \( m \) is the slope of the line.
- \( b \) is the y-intercept, the point where the line crosses the y-axis.
Slope
The slope of a line, denoted by \( m \), is a measure of its steepness. It tells us how much \( y \) increases or decreases as \( x \) increases by 1 unit. The formula to find the slope between two points \((x_1, y_1)\) and \((x_2, y_2)\) on a line is given by:\[m = \frac{y_2 - y_1}{x_2 - x_1}\]The slope can be positive, negative, zero, or undefined:
- Positive slope: line rises from left to right.
- Negative slope: line falls from left to right.
- Zero slope: horizontal line.
- Undefined slope: vertical line.
Y-Intercept
The y-intercept of a line is the value of \( y \) when \( x = 0 \). It is represented by \( b \) in the slope-intercept form \( y = mx + b \). In practical terms, it is the point where the line crosses the y-axis:- The y-intercept provides a starting point for graphing the line.In our example, after calculating using the point \((4, 3)\), the y-intercept \( b \) was found to be 7. Thus, the line crosses the y-axis at \( (0, 7) \). This means if you start at the origin, the line will pass through the point on the y-axis at 7.
Coordinate Geometry
Coordinate geometry, also known as analytic geometry, involves studying geometry using a coordinate system. It helps us understand concepts of lines and curves algebraically.
- Its foundation lies in the coordinate plane which consists of two axes: x-axis (horizontal) and y-axis (vertical).
- Each point on the plane is represented as \((x, y)\), a pair of numerical values showing its direction and distance from the origin \((0, 0)\).