Chapter 6: Problem 1
State the gradient and vertical intercept of (a) \(y=8 x-3\) (b) \(y=3 t-2\) (c) \(y=9\) (d) \(y=-3 t\) (e) \(f(x)=-3-4 x\)
Short Answer
Expert verified
(a) Gradient: 8, Intercept: -3; (b) Gradient: 3, Intercept: -2; (c) Gradient: 0, Intercept: 9; (d) Gradient: -3, Intercept: 0; (e) Gradient: -4, Intercept: -3.
Step by step solution
01
Understanding the Form of the Equation
The general form of a linear equation is \( y = mx + c \), where \( m \) is the gradient, and \( c \) is the vertical intercept of the line. This pattern will help us identify the values for each part.
02
Analyzing Equation (a) \( y = 8x - 3 \)
Comparing \( y = 8x - 3 \) to the general form, we identify \( m = 8 \) and \( c = -3 \). Thus, the gradient is 8, and the vertical intercept is -3.
03
Analyzing Equation (b) \( y = 3t - 2 \)
Treating \( t \) as the same as \( x \) in the form, compare \( y = 3t - 2 \) to \( y = mx + c \). Here, \( m = 3 \) and \( c = -2 \). The gradient is 3, and the vertical intercept is -2.
04
Analyzing Equation (c) \( y = 9 \)
This equation is a horizontal line, thus \( m = 0 \) because there is no \( x \) term. The vertical intercept \( c \) is 9. The gradient is 0, and the vertical intercept is 9.
05
Analyzing Equation (d) \( y = -3t \)
Here, compare \( y = -3t \) to the form \( y = mx + c \). We see \( m = -3 \) and \( c = 0 \) as there is no additional constant. The gradient is -3, and the vertical intercept is 0.
06
Analyzing Equation (e) \( f(x) = -3 - 4x \)
Rearranging it to \( y = -4x - 3 \), compare with \( y = mx + c \). This gives \( m = -4 \) and \( c = -3 \). The gradient is -4, and the vertical intercept is -3.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Gradient
The gradient of a line, often known as the slope, describes how steep the line is. It is represented by the letter \( m \) in the equation of a line in the slope-intercept form, \( y = mx + c \). The gradient tells us how much \( y \) changes for a unit change in \( x \).
Here’s how to understand it:
Here’s how to understand it:
- A positive gradient means the line rises as it moves from left to right.
- A negative gradient means the line falls as you move along the horizontal axis.
- A gradient of zero indicates a perfectly horizontal line, where \( y \) does not change regardless of the \( x \) value.
Vertical Intercept
The vertical intercept, also known as the \( y \)-intercept, is the point where the line crosses the \( y \)-axis. In the slope-intercept form, \( y = mx + c \), the \( c \) represents the vertical intercept. This is the value of \( y \) when \( x \) equals 0.
To identify the vertical intercept, look for the constant term in the equation. Some key points include:
To identify the vertical intercept, look for the constant term in the equation. Some key points include:
- For the equation \( y = 8x - 3 \), the vertical intercept is \( -3 \). This means that when \( x \) is 0, \( y \) is \(-3\).
- If there is no constant term, it means the vertical intercept is \( 0 \), and the line passes through the origin. For example, in \( y = -3t \), the intercept is \( 0 \).
Linear Functions
Linear functions are foundational in algebra and are represented by straight lines on a graph. They show a constant rate of change, making them predictable and easy to understand. The general form of a linear equation is \( y = mx + c \).
Characteristics of linear functions include:
Characteristics of linear functions include:
- They form a straight line when plotted on a graph.
- The rate of change is constant across all values of \( x \); this is the gradient.
- The behavior of the line either increases, decreases, or remains constant depending on the gradient.
Slope-Intercept Form
The slope-intercept form is one of the most common ways of expressing a linear equation. It is written as \( y = mx + c \), where:
Here’s why it’s useful:
- \( m \) represents the slope or gradient of the line.
- \( c \) is the \( y \)-intercept, where the line crosses the \( y \)-axis.
Here’s why it’s useful:
- Quickly determine how the output \( y \) changes based on different inputs \( x \).
- Helps in graphing lines with ease by knowing just the slope and where to start on the \( y \)-axis.
- Facilitates easier comparison between different linear equations.