Chapter 1: Problem 31
In Problems 29-34, find an equation for each line. Then write your answer in the form \(A x+B y+C=0 .\) With \(y\) -intercept 3 and slope 2
Short Answer
Expert verified
The equation in standard form is \(2x - y - 3 = 0\).
Step by step solution
01
Identify Slope-Intercept Form
Given that the slope is 2 and the y-intercept is 3, we start by writing the slope-intercept form of the line, which is \(y = mx + b\). Here, \(m = 2\) and \(b = 3\), so the equation is \(y = 2x + 3\).
02
Convert to Standard Form
To convert the equation \(y = 2x + 3\) into the standard form \(Ax + By + C = 0\), we rearrange the terms. Subtract \(2x\) from both sides to get \(-2x + y = 3\).
03
Adjust to Desired Format
The standard form equation is typically written with positive \(x\) coefficient. Multiply all terms in \(-2x + y = 3\) by -1 to get \(2x - y = -3\). Thus, in the form \(A x+B y+C=0\), it is \(2x - y - 3 = 0\).
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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 straightforward way to express the equation of a line. This form is written as \(y = mx + b\), where \(m\) represents the slope and \(b\) represents the y-intercept.
- "\(m\)" or slope is the amount by which \(y\) increases when \(x\) increases by 1.
- "\(b\)" or y-intercept is the value of \(y\) when \(x = 0\).
- Slope: \(m = 2\), meaning for each unit increase in \(x\), \(y\) increases by 2 units.
- Intercept: \(b = 3\), meaning the line crosses the y-axis at \(y = 3\).
Standard Form
The standard form of an equation of a line is expressed as \(Ax + By + C = 0\) where \(A\), \(B\), and \(C\) are integers. This form is commonly used in solving systems of linear equations or for certain algebraic manipulations.
- In standard form, \(A\) should be a non-negative integer.
- Some people prefer the standard form because it doesn’t involve fractions or decimals as coefficients.
- Rearrange it to \(-2x + y = 3\).
- Multiply all terms by -1 to ensure \(A\) is positive, resulting in \(2x - y - 3 = 0\).
Y-Intercept
The y-intercept of a line is the point where the line crosses the y-axis. In the context of the slope-intercept form \(y = mx + b\), the y-intercept is represented by \(b\), which is a constant.Here’s why the y-intercept is important:
- It provides a starting point on a graph where the line begins when \(x = 0\).
- It can help in graphing the line quickly because you know precisely where it intersects the y-axis.
- The y-intercept is \(3\).
- Thus, the line crosses the y-axis at the point \((0, 3)\).
Slope
The slope of a line is a measure of its steepness and direction. In the slope-intercept form \(y = mx + b\), the slope is represented by \(m\).
- If \(m > 0\), the line slopes upwards as you move from left to right.
- If \(m < 0\), the line slopes downwards.
- "Rise" is the change in \(y\).
- "Run" is the change in \(x\).
- With every one unit increase in \(x\), \(y\) increases by 2 units.
- The slope determines how steep the line is and indicates how quickly \(y\) changes with respect to \(x\).