Algebra 1 : Algebra 1

Study concepts, example questions & explanations for Algebra 1

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Example Questions

Example Question #93 : How To Find Out If Lines Are Parallel

Determine if the lines are parallel and find their slopes:

\(\displaystyle 4y-2=x\)

\(\displaystyle 6y-3=2x\)

Possible Answers:

\(\displaystyle No: slopes:\frac{1}{4},\frac{1}{3}\)

\(\displaystyle Yes: slope=\frac{1}{3}\)

\(\displaystyle Yes: slope=-1\)

\(\displaystyle Yes: slope=\frac{1}{2}\)

Correct answer:

\(\displaystyle No: slopes:\frac{1}{4},\frac{1}{3}\)

Explanation:

In order to determine if two lines have the same slope first write them according to slope-intercept form, where "m" is the slope of the line:

\(\displaystyle y=mx+b\)

Do that for each line:

\(\displaystyle 4y-2=x\rightarrow 4y=x+2\rightarrow y=\frac{1}{4}x+\frac{1}{2}\)

\(\displaystyle 6y-3=2x\rightarrow 6y=2x+3\rightarrow y=\frac{1}{3}x+\frac{1}{2}\)

The first line has a slope of 1/4, while the second has a slope of 1/3 meaning the lines are not parallel.

Example Question #4101 : Algebra 1

Determine if the lines are parallel and find their slopes:

\(\displaystyle x-y=4\)

\(\displaystyle 2x-3y=4\)

Possible Answers:

\(\displaystyle Yes: slope=\frac{2}{3}\)

\(\displaystyle Yes: slope=\frac{3}{2}\)

\(\displaystyle Yes: slope=-1\)

\(\displaystyle No: slopes=1,\frac{2}{3}\)

Correct answer:

\(\displaystyle No: slopes=1,\frac{2}{3}\)

Explanation:

In order to determine if two lines have the same slope first write them according to slope-intercept form, where "m" is the slope of the line:

\(\displaystyle y=mx+b\)

Do that for each line:

\(\displaystyle x-y=4\rightarrow -y=-x+4\rightarrow y=x-4\)

\(\displaystyle 2x-3y=4\rightarrow -3y=-2x+4\rightarrow y=\frac{2}{3}x-\frac{4}{3}\)

The first line has a slope of 1, while the second has a slope of 2/3 meaning the lines are not parallel.

Example Question #571 : Equations Of Lines

Determine if the lines are parallel and find their slopes:

\(\displaystyle 6x+y=12\)

\(\displaystyle 5x+2y=15\)

Possible Answers:

\(\displaystyle No: slopes=1,-4\)

\(\displaystyle No: slopes=-6,\frac{-5}{2}\)

\(\displaystyle Yes: slope=-2\)

\(\displaystyle Yes: slope=-6\)

Correct answer:

\(\displaystyle No: slopes=-6,\frac{-5}{2}\)

Explanation:

In order to determine if two lines have the same slope first write them according to slope-intercept form, where "m" is the slope of the line:

\(\displaystyle y=mx+b\)

Do that for each line:

\(\displaystyle 6x+y=12\rightarrow y=-6x+12\)

\(\displaystyle 5x+2y=15\rightarrow 2y=-5x+15\rightarrow y=\frac{-5}{2}x+3\)

The first line has a slope of -6, while the second has a slope of -5/2 meaning the lines are not parallel.

Example Question #141 : Parallel Lines

Determine if the lines are parallel and find their slopes:

\(\displaystyle y-3x=12\)

\(\displaystyle y+2x=6\)

Possible Answers:

\(\displaystyle Yes: slope=\frac{1}{3}\)

\(\displaystyle No: slopes=3,-2\)

\(\displaystyle No: slopes=-1,\frac{2}{3}\)

\(\displaystyle Yes: slope=-1\)

Correct answer:

\(\displaystyle No: slopes=3,-2\)

Explanation:

In order to determine if two lines have the same slope first write them according to slope-intercept form, where "m" is the slope of the line:

\(\displaystyle y=mx+b\)

Do that for each line:

\(\displaystyle y-3x=12\rightarrow y=3x+12\)

\(\displaystyle y+2x=6\rightarrow y=-2x+6\)

The first line has a slope of 3, while the second has a slope of -2 meaning the lines are not parallel.

Example Question #811 : Functions And Lines

Find the line that is parallel to the following:

\(\displaystyle 6y = -42x + 36\)

Possible Answers:

\(\displaystyle 7y = -42x -14\)

\(\displaystyle y = -42x - 26\)

\(\displaystyle -8y = 56x + 64\)

\(\displaystyle 6y = -36x + 6\)

\(\displaystyle -9x = -63x + 9\)

Correct answer:

\(\displaystyle -8y = 56x + 64\)

Explanation:

Two lines are parallel when they have the same slope.  We can compare slopes when we write the equation of the line in slope-intercept form

\(\displaystyle y = mx+b\)

where m is the slope.  Given the original equation

\(\displaystyle 6y = -42x + 36\)

we must write it in slope-intercept form to find the slope.  To do this, we will divide each term by 6.  We get

\(\displaystyle \frac{6y}{6} = \frac{-42x}{6} + \frac{36}{6}\)

\(\displaystyle y = -7x + 6\)

Therefore, the slope of the original line is -7.  A line that is parallel to this line needs to have a slope of -7.

 

Let's look at the equation of the line 

\(\displaystyle -8y = 56x + 64\)

We must write it in slope-intercept form.  To do this, we will divide each term by -8.  We get

\(\displaystyle \frac{-8y}{-8} = \frac{56x}{-8} + \frac{64}{-8}\)

\(\displaystyle y = -7x - 8\)

The slope of this line is -7.  Therefore, it is parallel to the original line.

Example Question #101 : How To Find Out If Lines Are Parallel

Given the equations \(\displaystyle y=-3x+9\) and \(\displaystyle y=1-3x\), are the two lines parallel to each other?

Possible Answers:

\(\displaystyle \textup{}\)No, the lines are NOT parallel since slopes are NOT alike.

\(\displaystyle \textup{}\)Yes, the lines are parallel since y-intercepts are alike.

Yes, the lines are parallel since slopes are alike.

\(\displaystyle \textup{}\)No, the lines are NOT parallel since y-intercepts are NOT alike.

\(\displaystyle \textup{}\)Yes, the lines are parallel since slopes are NOT alike.

Correct answer:

Yes, the lines are parallel since slopes are alike.

Explanation:

For the lines to be parallel, both the lines must have similar slopes.

Write the slope-intercept form.

\(\displaystyle y=mx+b\)

The \(\displaystyle m\) represents the slope.  Both of the equation have a slope of negative three.  Therefore, both lines are parallel.

The answer is:  \(\displaystyle \textup{Yes, the lines are parallel since slopes are alike.}\)

Example Question #101 : How To Find Out If Lines Are Parallel

Which of the following lines is parallel to

\(\displaystyle 6y = -42x + 18\)

Possible Answers:

\(\displaystyle y = -42x + 2\)

\(\displaystyle 6y = 3x + 9\)

\(\displaystyle y = -36x + 12\)

\(\displaystyle y = \frac{1}{7}x + 4\)

\(\displaystyle y = -7x + 1\)

Correct answer:

\(\displaystyle y = -7x + 1\)

Explanation:

If two lines are parallel, then they have the same slope.  To find the slope of a line, we write it in slope-intercept form

\(\displaystyle y = mx+b\)

where m is the slope.  So given the equation

\(\displaystyle 6y = -42x + 18\)

we must solve for y.  To do that, we will divide each term by 6.  We get

\(\displaystyle \frac{6y}{6} = \frac{-42x}{6} + \frac{18}{6}\)

\(\displaystyle y = -7x + 3\)

We can see the slope of this line is -7.  Therefore, this line is parallel to the line 

\(\displaystyle y = -7x + 1\)

because it also has a slope of -7.

Example Question #101 : How To Find Out If Lines Are Parallel

How can you tell if two lines are parallel?

Possible Answers:

\(\displaystyle \text{The slope of one line is positive, and the slope of the other line is negative.}\)

\(\displaystyle \text{The slope of both lines are the same.}\)

\(\displaystyle \text{The slope of both lines are opposite reciprocals.}\)

\(\displaystyle \text{The y-intercepts of both lines are opposite reciprocals.}\)

\(\displaystyle \text{The y-intercepts of both lines are the same.}\)

Correct answer:

\(\displaystyle \text{The slope of both lines are the same.}\)

Explanation:

When looking at parallel lines, the slopes on both lines must be the same.  The y-intercept (or any other characteristic) of the lines do not matter. 

As long as the slopes are the same, the lines are parallel.

Example Question #573 : Equations Of Lines

Which of the following lines are parallel to \(\displaystyle y=3x+4\)?

Possible Answers:

\(\displaystyle x=3\)

\(\displaystyle y=-\frac{1}{3}x\)

\(\displaystyle y=3x+5\)

\(\displaystyle y=\frac{1}{3}x\)

\(\displaystyle y=3\)

Correct answer:

\(\displaystyle y=3x+5\)

Explanation:

In order to determine whether if the lines are parallel, the lines must never intersect and share a similar slope to the equation given in the problem.

The equation is already in the form of:  \(\displaystyle y=mx+b\)

The variable \(\displaystyle m\) denotes the slope of the function.

The slope of the other line must be three to be parallel.  

The only possible answer is:  \(\displaystyle y=3x+5\)

Example Question #107 : How To Find Out If Lines Are Parallel

Determine if the two lines are parallel

\(\displaystyle y=2x+7\)

\(\displaystyle y=3x-5\)

Possible Answers:

Lines are dependent

Lines are NOT parallel

Lines are parallel

Cannot be determined

Correct answer:

Lines are NOT parallel

Explanation:

When given the equations of a line in slope-intercept form 

\(\displaystyle y=mx+b\)

the lines are parallel if both of the following conditions are met

  • \(\displaystyle m\) is the same value for both equations
  • \(\displaystyle b\) are different values in the two equations

For the lines

\(\displaystyle y=2x+7\)

\(\displaystyle y=3x-5\)

we see that the \(\displaystyle m\) values are not the same and as such

the lines are NOT parallel.

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