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Access these online resources for additional instruction and practice with graphs of linear functions.

Key concepts

  • Linear functions may be graphed by plotting points or by using the y -intercept and slope. See [link] and [link] .
  • Graphs of linear functions may be transformed by using shifts up, down, left, or right, as well as through stretches, compressions, and reflections. See [link] .
  • The y -intercept and slope of a line may be used to write the equation of a line.
  • The x -intercept is the point at which the graph of a linear function crosses the x -axis. See [link] and [link] .
  • Horizontal lines are written in the form, f ( x ) = b . See [link] .
  • Vertical lines are written in the form, x = b . See [link] .
  • Parallel lines have the same slope.
  • Perpendicular lines have negative reciprocal slopes, assuming neither is vertical. See [link] .
  • A line parallel to another line, passing through a given point, may be found by substituting the slope value of the line and the x - and y -values of the given point into the equation, f ( x ) = m x + b , and using the b that results. Similarly, the point-slope form of an equation can also be used. See [link] .
  • A line perpendicular to another line, passing through a given point, may be found in the same manner, with the exception of using the negative reciprocal slope. See [link] and [link] .
  • A system of linear equations may be solved setting the two equations equal to one another and solving for x . The y -value may be found by evaluating either one of the original equations using this x -value.
  • A system of linear equations may also be solved by finding the point of intersection on a graph. See [link] and [link] .

Section exercises

Verbal

If the graphs of two linear functions are parallel, describe the relationship between the slopes and the y -intercepts.

The slopes are equal; y -intercepts are not equal.

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If the graphs of two linear functions are perpendicular, describe the relationship between the slopes and the y -intercepts.

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If a horizontal line has the equation f ( x ) = a and a vertical line has the equation x = a , what is the point of intersection? Explain why what you found is the point of intersection.

The point of intersection is ( a , a ) . This is because for the horizontal line, all of the y coordinates are a and for the vertical line, all of the x coordinates are a . The point of intersection will have these two characteristics.

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Explain how to find a line parallel to a linear function that passes through a given point.

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Explain how to find a line perpendicular to a linear function that passes through a given point.

First, find the slope of the linear function. Then take the negative reciprocal of the slope; this is the slope of the perpendicular line. Substitute the slope of the perpendicular line and the coordinate of the given point into the equation y = m x + b and solve for b . Then write the equation of the line in the form y = m x + b by substituting in m and b .

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Algebraic

For the following exercises, determine whether the lines given by the equations below are parallel, perpendicular, or neither parallel nor perpendicular:

4 x 7 y = 10 7 x + 4 y = 1

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Questions & Answers

a colony of bacteria is growing exponentially doubling in size every 100 minutes. how much minutes will it take for the colony of bacteria to triple in size
Divya Reply
what is the importance knowing the graph of circular functions?
Arabella Reply
can get some help basic precalculus
ismail Reply
What do you need help with?
Andrew
how to convert general to standard form with not perfect trinomial
Camalia Reply
can get some help inverse function
ismail
Rectangle coordinate
Asma Reply
how to find for x
Jhon Reply
it depends on the equation
Robert
whats a domain
mike Reply
The domain of a function is the set of all input on which the function is defined. For example all real numbers are the Domain of any Polynomial function.
Spiro
foci (–7,–17) and (–7,17), the absolute value of the differenceof the distances of any point from the foci is 24.
Churlene Reply
difference between calculus and pre calculus?
Asma Reply
give me an example of a problem so that I can practice answering
Jenefa Reply
x³+y³+z³=42
Robert
dont forget the cube in each variable ;)
Robert
of she solves that, well ... then she has a lot of computational force under her command ....
Walter
what is a function?
CJ Reply
I want to learn about the law of exponent
Quera Reply
explain this
Hinderson Reply
what is functions?
Angel Reply
A mathematical relation such that every input has only one out.
Spiro
yes..it is a relationo of orders pairs of sets one or more input that leads to a exactly one output.
Mubita
Is a rule that assigns to each element X in a set A exactly one element, called F(x), in a set B.
RichieRich
If the plane intersects the cone (either above or below) horizontally, what figure will be created?
Feemark Reply
Practice Key Terms 5

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Source:  OpenStax, Precalculus. OpenStax CNX. Jan 19, 2016 Download for free at https://legacy.cnx.org/content/col11667/1.6
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