Graphical Representation Practice Problems - Linear Functions

Master graphical representation of direct proportionality functions with step-by-step practice problems. Learn to identify slopes, y-intercepts, and graph linear equations.

📚Practice Graphing Linear Functions and Direct Proportionality
  • Graph linear functions using slope and y-intercept from y = ax + b
  • Identify ascending, descending, and horizontal lines from equation coefficients
  • Determine y-intercept points and their impact on graph position
  • Create value tables to plot accurate coordinate points
  • Recognize direct proportionality relationships in linear equations
  • Sketch graphs based on slope analysis and intersection points

Understanding Graphical Representation

Complete explanation with examples

The graphical representation of a function that represents direct proportionality is actually the ability to express an algebraic expression through a graph.

As it is a direct proportionality, the graph will be of a straight line.

A function that represents direct proportionality is a linear function of the family y=ax+b y=ax+b .

The graphical representation of this function is a straight line that is ascending, descending, or parallel to the X X axis but never parallel to the Y Y axis.

Note: we observe the line from left to right.

We can now recognize in the equation of the line what the graphical representation of each function looks like:

(only when the equation is explicit Y Y is isolated on one side and its coefficient is 1 1 )

A - Graphs of Direct Proportionality Functions

Detailed explanation

Practice Graphical Representation

Test your knowledge with 9 quizzes

A straight line with the slope 9 passes through the point \( (-5,-8) \).

Which of the following equations corresponds to the line?

Examples with solutions for Graphical Representation

Step-by-step solutions included
Exercise #1

Which statement is true according to the graph below?

111222333444555666777111222333444555666777888000

Step-by-Step Solution

If we plot all the points, we'll notice that point (3,5) (3,5) is the correct one, because:

x=3,y=5 x=3,y=5

And they intersect exactly on the line where the graph passes.

Answer:

The graph passes through (3,5) (3,5) .

Video Solution
Exercise #2

Which statement best describes the graph below?

xy

Step-by-Step Solution

To solve this problem, let's analyze the given graph:

  • The graph shows a straight line plotted on a coordinate grid.
  • The line is drawn from the lower-left corner to the upper-right corner. This indicates that for increasing values of x x , the corresponding y y values also increase.

According to the properties of linear graphs:

  • A line with a positive slope rises from left to right, which indicates an ascending function.
  • A line with a negative slope falls from left to right, which indicates a descending function.
  • A line with a zero slope is horizontal, indicating a constant function.

Given that the line in the graph rises as x x increases, it has a positive slope. Therefore, it represents an ascending function.

Thus, the correct statement about the graph is: The graph represents an ascending function.

Answer:

The graph represents an ascending function.

Exercise #3

Choose the correct answer

xy

Step-by-Step Solution

The blue line is a straight line, therefore it remains constant.

Let's note that the red line is rising because it starts in the negative part (negative values) and rises to the positive part (positive values).

Therefore, the correct answer is D.

Answer:

Answers B and C are correct

Exercise #4

Does line I pass through the origin point of the axes?

111222333444555666777–5–5–5–4–4–4–3–3–3–2–2–2–1–1–1111222333000xyIII

Step-by-Step Solution

Let's first remember that the origin of the coordinate system is (0,0) (0,0) .

We'll highlight the point on the graph, noting that it doesn't lie on any of the plotted lines.

Therefore, the answer is C; If we plot the point (3,1) (3,1) , then we'll see that it lies on line I (the blue one).

Answer:

No, it passes through (3,1) (3,1) .

Video Solution
Exercise #5

At which point does the graph of the first function (I) intersect the graph of the second function (II)?

111222333444555666777–5–5–5–4–4–4–3–3–3–2–2–2–1–1–1111222333000xyIII

Step-by-Step Solution

Let's pay attention to the point where the lines intersect. We'll mark it.

We'll find that:

X=4,Y=2 X=4,Y=2

Therefore, the point is:

(4,2) (4,2)

Answer:

(4,2) (4,2)

Video Solution

Frequently Asked Questions

How do you graph a linear function from its equation?

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To graph a linear function y = ax + b, first identify the slope (a) and y-intercept (b). Plot the y-intercept point on the y-axis, then use the slope to find additional points by moving right 1 unit and up/down according to the slope value.

What does the slope tell you about a line's direction?

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The slope coefficient determines line direction: when a > 0, the line ascends from left to right; when a < 0, the line descends; when a = 0, the line is horizontal and parallel to the x-axis.

How do you find where a line crosses the y-axis?

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The y-intercept is the coefficient b in the equation y = ax + b. This tells you exactly where the line crosses the y-axis at point (0, b). If b is positive, it crosses above the origin; if negative, below the origin.

What is direct proportionality in linear functions?

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Direct proportionality occurs when y = ax (where b = 0), meaning the line passes through the origin. For every unit increase in x, y increases by a constant factor of 'a', creating a straight line through (0,0).

How do you create a table of values for graphing?

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Choose several x-values (like -2, -1, 0, 1, 2), substitute each into your equation y = ax + b, calculate the corresponding y-values, then plot these coordinate pairs (x,y) on your graph and connect them with a straight line.

Can a linear function line be vertical?

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No, linear functions of the form y = ax + b cannot be vertical lines. Vertical lines are parallel to the y-axis and cannot be expressed as functions since they fail the vertical line test (one x-value would have multiple y-values).

What's the difference between positive and negative slopes in graphs?

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Positive slopes (a > 0) create ascending lines that rise from left to right, while negative slopes (a < 0) create descending lines that fall from left to right. The steeper the absolute value of the slope, the more dramatic the rise or fall.

How do you identify direct proportionality from a graph?

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A graph represents direct proportionality when the line passes through the origin (0,0) and maintains a constant slope. This creates a straight line where the ratio of y to x remains constant for all points on the line.

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