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 standard form is \(2x - y = -3\).
Step by step solution
01
Identify the Given Information
We are asked to find an equation of a line with a given slope and y-intercept. The slope (m) is 2 and the y-intercept (c) is 3.
02
Formulate the Slope-Intercept Equation
Recall the formula for the slope-intercept form of a line: \[ y = mx + c \]Substitute the given slope and y-intercept: \[ y = 2x + 3 \]
03
Convert to Standard Form
We need to convert the slope-intercept form to the standard form \(Ax + By + C = 0\). Start by rearranging:\[ y = 2x + 3 \]Subtract 2x from both sides:\[ -2x + y = 3 \]
04
Finalize the Standard Form
The equation \(-2x + y = 3\) isn't quite in standard form since A should be positive. Multiply the whole equation by -1:\[ 2x - y = -3 \]
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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 one of the most commonly used ways to write the equation of a line in algebra. The general format of this equation is \( y = mx + c \). Here, \( m \) represents the slope of the line, and \( c \) stands for the y-intercept. This form is particularly useful for quickly identifying how a line behaves on a graph. To better grasp this concept, let's consider:
- **Slope (\( m \)):** It determines the steepness and the direction of the line. If \( m \) is positive, the line slopes upwards; if negative, it slopes downwards.
- **Y-Intercept (\( c \)):** This is where the line crosses the y-axis, indicating the value of \( y \) when \( x \) is 0.
standard form
The standard form of a linear equation is another essential format, often expressed as \( Ax + By + C = 0 \). In this equation:
- \( A \), \( B \), and \( C \) are integers, with \( A \) typically kept positive.
- Both \( A \) and \( B \) cannot be zero simultaneously because this would not define a line.
- To find the x-intercept, set \( y = 0 \) and solve for \( x \).
- Conversely, to find the y-intercept, set \( x = 0 \) and solve for \( y \).
y-intercept
The y-intercept is a fundamental part of linear equations, as it indicates the point at which a line crosses the y-axis of a graph. It is denoted by \( c \) in the slope-intercept form \( y = mx + c \). Understanding the y-intercept can simplify graphing and interpreting linear relationships:
- **Visual Interpretation:** If you plot the line on a graph, you would place a point on the y-axis at \( y = c \). This is your starting point when drawing the line.
- **Equation Insight:** The y-intercept helps you see how changes in \( x \) affect \( y \) when the line crosses the y-axis.
slope
The slope of a line is a crucial concept in algebra, contributing significantly to understanding how a line behaves on a graph. Denoted as \( m \) in the equation \( y = mx + c \), the slope indicates the rate at which \( y \) changes as \( x \) changes. It is often referred to as the line's 'steepness'. Here are some key details about slope:
- **Positive Slope:** If \( m > 0 \), the line inclines upward from left to right.
- **Negative Slope:** If \( m < 0 \), the line declines downward from left to right.
- **Zero Slope:** If \( m = 0 \), the line is horizontal, indicating no change in \( y \) regardless of changes in \( x \).
- **Undefined Slope:** Vertical lines have an undefined slope, as the change in \( x \) is zero.Understanding slope helps in predicting how a line extends as \( x \) values increase or decrease, which is pivotal in many applications such as physics and economics.