Linear Functions Practice Problems y=mx+b - Slope & Y-Intercept

Master linear functions with practice problems covering slope, y-intercept, graphing, and real-world applications. Build confidence with step-by-step solutions.

📚What You'll Master in Linear Functions Practice
  • Identify slope (m) and y-intercept (b) from linear equations
  • Graph linear functions using two points method
  • Find equations of straight lines from given points
  • Solve linear inequalities graphically and algebraically
  • Determine positive and negative regions of linear functions
  • Apply linear functions to real-world phenomena and situations

Understanding Linear Functions

Complete explanation with examples

A linear function, as it is called, is an algebraic expression that represents the graph of a straight line.

When we talk about functions, it's important to highlight that the graphs of functions are represented in an axis system where there is a horizontal axis X X and a vertical axis Y Y .

A - Linear Function

Linear functions can be expressed by the expressions y=mx y = mx or y=mx+b y = mx + b , where m represents the slope of the line while b b (when it exists) represents the y-intercept.

To plot a linear function, all we need are 2 2 points. If the linear function is given, you can substitute a value for X X and obtain the corresponding Y Y value.

Detailed explanation

Practice Linear Functions

Test your knowledge with 20 quizzes

Given the linear function of the drawing.

What is the negative domain of the function?

xy

Examples with solutions for Linear Functions

Step-by-step solutions included
Exercise #1

Look at the linear function represented in the diagram.

When is the function positive?

–8–8–8–7–7–7–6–6–6–5–5–5–4–4–4–3–3–3–2–2–2–1–1–1111222333444555666777888–5–5–5–4–4–4–3–3–3–2–2–2–1–1–1111222333000

Step-by-Step Solution

The function is positive when it is above the X-axis.

Let's note that the intersection point of the graph with the X-axis is:

(2,0) (2,0) meaning any number greater than 2:

x > 2

Answer:

x>2

Video Solution
Exercise #2

Look at the function shown in the figure.

When is the function positive?

xy-4-7

Step-by-Step Solution

The function we see is a decreasing function,

Because as X increases, the value of Y decreases, creating the slope of the function.

We know that this function intersects the X-axis at the point x=-4

Therefore, we can understand that up to -4, the values of Y are greater than 0, and after -4, the values of Y are less than zero.

Therefore, the function will be positive only when

X < -4

 

Answer:

-4 > x

Video Solution
Exercise #3

What is the solution to the following inequality?

10x43x8 10x-4≤-3x-8

Step-by-Step Solution

In the exercise, we have an inequality equation.

We treat the inequality as an equation with the sign -=,

And we only refer to it if we need to multiply or divide by 0.

 10x43x8 10x-4 ≤ -3x-8

We start by organizing the sections:

10x+3x48 10x+3x-4 ≤ -8

13x48 13x-4 ≤ -8

13x4 13x ≤ -4

Divide by 13 to isolate the X

x413 x≤-\frac{4}{13}

Let's look again at the options we were asked about:

Answer A is with different data and therefore was rejected.

Answer C shows a case where X is greater than413 -\frac{4}{13} , although we know it is small, so it is rejected.

Answer D shows a case (according to the white circle) where X is not equal to413 -\frac{4}{13} , and only smaller than it. We know it must be large and equal, so this answer is rejected.

 

Therefore, answer B is the correct one!

Answer:

Video Solution
Exercise #4

For the function in front of you, the slope is?

XY

Step-by-Step Solution

For this problem, we need to determine the nature of the slope for a given straight line on a graph.

Based on the graph provided, the red line starts at a higher point on the left (Y-axis) and moves downward toward a lower point on the right (X-axis). This indicates that as one moves from left to right across the graph, the function decreases in value. Consequently, this is typical of a line that has a negative slope.

The slope of a line is typically defined as the "rise over the run," or the ratio of the change in the vertical direction to the change in the horizontal direction. Here, as we proceed from left to right, the line goes "downwards" (negative rise), establishing a negative slope.

Thus, we can conclude that the slope of the line is negative.

Therefore, the solution to the problem is Negative slope.

Answer:

Negative slope

Video Solution
Exercise #5

For the function in front of you, the slope is?

XY

Step-by-Step Solution

To solve this problem, follow these steps:

  • Step 1: Observe the given graph and the plotted line.
  • Step 2: Determine the direction of the line as it moves from left to right across the graph.
  • Step 3: Understand that a line moving downwards from left to right represents a negative slope.

Now, let's work through these steps:

Step 1: The graph shows a straight line that starts higher on the left side and descends towards the right side.

Step 2: As the line moves from left to right, it descends. This is a key indicator of the slope type.

Step 3: A line that moves downward from the left side to the right side of the graph (decreasing in height as it proceeds to the right) is characteristic of a negative slope. Conversely, a positive slope would show a line ascending as it moves rightward.

Therefore, the solution to the problem is the line has a negative slope.

Answer:

Negative slope

Video Solution

Frequently Asked Questions

How do you find the slope and y-intercept of a linear function?

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In the standard form y = mx + b, the slope is the coefficient m (the number multiplying x), and the y-intercept is the constant term b. For example, in y = 2x + 1, the slope is 2 and the y-intercept is 1.

What are the steps to graph a linear function?

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1. Identify two points by substituting x-values into the equation 2. Plot these points on the coordinate plane 3. Draw a straight line connecting the points 4. Extend the line in both directions with arrows

When is a linear function positive or negative?

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A linear function is positive when y > 0 (above the x-axis) and negative when y < 0 (below the x-axis). Find the x-intercept to determine where the function changes sign.

How do you know if a function is NOT linear?

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A function is NOT linear if: x is raised to a power (like x²), there's a square root of x, or the equation cannot be written in the form y = mx + b. Examples include y = x² and y = √x.

What does slope tell you about a linear function?

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Slope describes the steepness and direction of the line. If m > 0, the line slopes upward; if m < 0, it slopes downward; if m = 0, the line is horizontal (parallel to x-axis).

How do you find the equation of a line from two points?

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Use the slope formula m = (y₂ - y₁)/(x₂ - x₁) to find the slope, then substitute one point and the slope into y = mx + b to solve for b.

Can a linear function be parallel to the y-axis?

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No, a linear function can never be parallel to the y-axis. Such a line would be vertical (x = constant) and would not pass the vertical line test for functions.

What are different ways to write linear functions?

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Common forms include: y = mx + b (slope-intercept), y = mx (through origin), y = b (horizontal line), and rearranged forms like mx - y = b that can be solved for y.

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