Pre-Algebra : Graphing Lines

Study concepts, example questions & explanations for Pre-Algebra

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Example Questions

Example Question #1 : Graphing Lines

What is the slope of the line with the equation \displaystyle y=13x+17?

Possible Answers:

\displaystyle m=-4

\displaystyle m=13

\displaystyle m=4

\displaystyle m=17

Correct answer:

\displaystyle m=13

Explanation:

In the standard form equation of a line, , the slope is represented by the variable .

In this case the line \displaystyle y=13x+17 has a slope of \displaystyle 13.

Therefore the answer is \displaystyle m=13.

Example Question #2 : Graphing Lines

What is the slope of the line that contains the points

\displaystyle (8,12) and \displaystyle (9,-7)?

Possible Answers:

\displaystyle m=-19

\displaystyle m=\frac{1}{2}

\displaystyle m=-13

\displaystyle m=8

\displaystyle m=-13

Correct answer:

\displaystyle m=-19

Explanation:

To find the slope of a line with two points you must properly plug the points into the slope equation for two points which is

\displaystyle m=\frac{Y-y}{X-x}

We must then properly assign the points to the equation as \displaystyle (X,Y) and \displaystyle (x,y).

In this case we will make \displaystyle (9,-7) our  and \displaystyle (8,12) our .

Plugging the points into the equation yields 

\displaystyle m=\frac{-7-12}{9-8}

Perform the math to arrive at 

\displaystyle m=\frac{-19}{1}

The answer is \displaystyle m=-19.

Example Question #3 : Graphing Lines

What is the slope of the line \displaystyle y=15x+13?

Possible Answers:

\displaystyle 15

\displaystyle 13

\displaystyle 5

\displaystyle x

Correct answer:

\displaystyle 15

Explanation:

In the standard form of a line \displaystyle y=mx+b the slope is represented by the variable \displaystyle m.

In this case the line \displaystyle y=15x+13 has a slope of \displaystyle 15.

The answer is \displaystyle 15.

Example Question #32 : Graphing

The equation of a line is \displaystyle y=4x-7.

What are the slope and the y-intercept?

Possible Answers:

Slope: \displaystyle \frac{1}{4}

y-intercept: \displaystyle (0,7)

Slope: \displaystyle 4

y-intercept: \displaystyle (0,7)

Slope: \displaystyle \frac{1}{4}

y-intercept: \displaystyle (0,-7)

Slope: \displaystyle 4

y-intercept: \displaystyle (0,-7)

Correct answer:

Slope: \displaystyle 4

y-intercept: \displaystyle (0,-7)

Explanation:

The equation of the line is written in slope-intercept form, \displaystyle y=mx+b, where \displaystyle m is the slope and \displaystyle b is the y-intercept. In this example, the y-intercept is a negative number.

\displaystyle y=4x-7

\displaystyle m=4

\displaystyle b=-7

Example Question #33 : Graphing

What is the y-intercept of the line \displaystyle y=16x+91?

Possible Answers:

\displaystyle (16,91)

\displaystyle (91,0)

\displaystyle (91,16)

\displaystyle (0,91)

Correct answer:

\displaystyle (0,91)

Explanation:

The y-intercept is the point at which the line intersects the y-axis.

It does this at .

We plug  in for  in our equation, \displaystyle y=16x+91, to give us \displaystyle y=16(0)+91.

Anything multiplied by  is , so \displaystyle y=91.

Our coordinates for the y-intercept are \displaystyle (0,91).

Example Question #3 : How To Identify A Point In Pre Algebra

What is the slope of the line \displaystyle y=15x+92?

Possible Answers:

\displaystyle m=5

\displaystyle m=35

\displaystyle m=15

\displaystyle m=92

Correct answer:

\displaystyle m=15

Explanation:

In the slope-intercept form of a line, , the slope is represented by the variable .

In this case the line

 

has a slope of .

The answer is \displaystyle m=15.

Example Question #1 : How To Identify A Point In Pre Algebra

What is the y-intercept of the line \displaystyle y=31x-65?

Possible Answers:

\displaystyle (-65,0)

\displaystyle (0,31)

\displaystyle (31,0)

\displaystyle (0,-65)

Correct answer:

\displaystyle (0,-65)

Explanation:

In the slope-intercept form of a line, , the y-intercept is when the line intersects the y-axis.

It does this at .

So we plug  in for  in our equation

\displaystyle y=31x-65 

to give us

\displaystyle y=31(0)-65

Anything multiplied by  is  so

\displaystyle y=-65

Our coordinates for the y-intercept are \displaystyle (0,-65).

Example Question #4 : How To Identify A Point In Pre Algebra

What is the slope of a line that is parallel to \displaystyle y=16x+17?

Possible Answers:

\displaystyle m=-\frac{1}{16}

\displaystyle m=17

\displaystyle m=-16

\displaystyle m=16

Correct answer:

\displaystyle m=16

Explanation:

Parallel lines have the same slope.

If an equation is in slope-intercept form, , we take the  from our equation and set it equal to the slope of our parallel line.

In this case \displaystyle m=16.

The slope of our parallel line is \displaystyle m=16.

Example Question #2 : Graphing Lines

What is the slope of the line that contains the points, \displaystyle (8,16) and \displaystyle (4,8)?

Possible Answers:

\displaystyle m=16

\displaystyle m=8

\displaystyle m=4

\displaystyle m=2

Correct answer:

\displaystyle m=2

Explanation:

To find the slope of a line with two points you must properly plug the points into the slope equation for two points which looks like

We must then properly assign the points to the equation as  and .

In this case we will make \displaystyle (8,16) our  and \displaystyle (4,8) our .

Plugging the points into the equation yields 

\displaystyle m=\frac{(16-8)}{(8-4)}

Perform the math to arrive at 

\displaystyle m=\frac{8}{4}

The answer is \displaystyle m=2.

Example Question #5 : Graphing Lines

What is the slope of the line that contains the points, \displaystyle (1,5) and \displaystyle (2,10)?

Possible Answers:

\displaystyle m=-\frac{1}{5}

\displaystyle m=5

\displaystyle m=-5

\displaystyle m=\frac{1}{5}

Correct answer:

\displaystyle m=5

Explanation:

To find the slope of a line with two points you must properly plug the points into the slope equation for two points which looks like

We must then properly assign the points to the equation as  and .

In this case we will make \displaystyle (2,10) our , and \displaystyle (1,5) our .

Plugging the points into the equation yields 

\displaystyle m=\frac{10-5}{2-1}

Perform the math to arrive at 

\displaystyle m=\frac{5}{1}

The answer is \displaystyle m=5.

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