Algebra 1 : Equations of Lines

Study concepts, example questions & explanations for Algebra 1

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Example Questions

Example Question #6 : How To Find The Equation Of A Parallel Line

Choose which of the four equations listed is parallel to the given equation. 

Possible Answers:

Correct answer:

Explanation:

 is the correct answer because when each term is divided by 2 in order to see the equation in terms of y, the slope of the equation is , which is the same as the slope in the given equation. Parallel lines have the same slope. 

Example Question #7 : How To Find The Equation Of A Parallel Line

Write an equation for a line that is parallel to  and has a y-intercept of 

Possible Answers:

Correct answer:

Explanation:

The equation of a line can be written using the expression  where  is the slope and  is the y-intercept. When lines are parallel to each other, it means that they have the same slope, so . The y-intercept is given in the problem as . This means that the equation would be .

Example Question #8 : How To Find The Equation Of A Parallel Line

Write the equation for a line parallel to passing through the point .

Possible Answers:

Correct answer:

Explanation:

In order to approach this problem, we need to be familiar with the slope-intercept equation of a line, where m is the slope and b is the y-intercept. The line that our line is supposed to be parallel to is . Lines that are parallel have the same slope, m, so the slope of our new line is . Since we don't know the y-intercept yet, for now we'll write our equation as just:

. We can solve for b using the point we know the line passes though, . We can plug in 4 for x and -2 for y to solve for b:

first we'll multiply to get 1:

 now we can subtract 1 from both sides to solve for b:

Now we can just go back to our equation and sub in -3 for b:

Example Question #9 : How To Find The Equation Of A Parallel Line

Find the equation of a line that is parallel to  and passes through the point .

Possible Answers:

None of the other answers.

A line cannot pass through this point and be parallel to the original line.

Correct answer:

None of the other answers.

Explanation:

Parallel lines have the same slope. So our line should have a slope of 2x. Next we use the point slope formula to find the equation of the line that passes through  and is parallel to .

Point slope formula:

 is the slope of the line parallel to  which passes through .

                                                                            

Example Question #5 : How To Find The Equation Of A Parallel Line

Find the equation of the line parallel to the given criteria:  and that passes through the point 

Possible Answers:

Correct answer:

Explanation:

Parallel lines have the same slope, so the slope of the new line will also have a slope 

Use point-slope form to find the equation of the new line.

Plug in known values and solve.

Example Question #11 : How To Find The Equation Of A Parallel Line

A line parallel to  passes through the points  and . Find the equation of this line. 

Possible Answers:

Correct answer:

Explanation:

This problem can be easily solved through using the point-slope formula:

 where  is the slope and  and  signify one of the given points (coordinates).

The problem provides us with two points, so that requirement is fulfilled. We may choose either one when substituting in our values. The only other requirement left is slope. The problem also provides us with this information, but it's not as obviously given. The problem specifies that the line of interest is parallel to By definition, lines are parallel when they have the same slope. Given that information, if the two lines are parallel, the line of interest will have the same slope as the given equation: . Therefore, we have our required point and the slope. Now we may substitute in all the information and solve for the equation. 

Here, we arbitrarily choose the point .

Example Question #12 : How To Find The Equation Of A Parallel Line

A line that passes through the points  and  is parallel to a line that has a slope of . What is the equation of this line?

Possible Answers:

Correct answer:

Explanation:

This problem can be easily solved through using the point-slope formula:

 where  is the slope and  and  signify one of the given points (coordinates).

The problem provides us with two points, so that requirement is fulfilled. We may choose either one when substituting in our values. The only other requirement left is slope. The problem also provides us with this information, but it's not as obviously given. The problem specifies that the line of interest is parallel to a line with a slope of By definition, lines are parallel when they have the same slope. Given that information, if the two lines are parallel, the line of interest will have the same slope as the given equation:. Therefore, we have our required point and the slope. Now we may substitute in all the information and solve for the equation. 

Here, we arbitrarily choose the point .

Example Question #13 : How To Find The Equation Of A Parallel Line

A line parallel to  passes through the points  and . Find the equation for this line. 

Possible Answers:

Correct answer:

Explanation:

This problem can be easily solved through using the point-slope formula:

 where  is the slope and  and  signify one of the given points (coordinates).

The problem provides us with two points, so that requirement is fulfilled. We may choose either one when substituting in our values. The only other requirement left is slope. The problem also provides us with this information, but it's not as obviously given. The problem specifies that the line of interest is parallel to  By definition, lines are parallel when they have the same slope. Given that information, if the two lines are parallel, the line of interest will have the same slope as the given equation: . Therefore, we have our required point and the slope. Now we may substitute in all the information and solve for the equation. 

Here, we arbitrarily choose the point .

Example Question #14 : How To Find The Equation Of A Parallel Line

Find the equation for the line that goes through the point  and is parallel to the line with the equation .

Possible Answers:

Correct answer:

Explanation:

The first thing we need to do is determine the slope of this parallel line. Recall that parallel lines have the same slope, so the slope of this new line must be .

Next, we must determine the -intercept of the line. The equation for a line is given to us by , and here we know three of the four variables in this new line: .

So when we plug in these numbers we get 

Multiply to get:

Subtract  from both sides to get:

Therefore, the equation for the line is:

Example Question #3962 : Algebra 1

If  is parallel to  and passes through the point , what is the equation of ?

Possible Answers:

Correct answer:

Explanation:

If f(x) is parallel to g(x) and passes through the point (-4,8), what is the equation of f(x)?

If f(x) is parallel to g(x), then it must have the same slope. 

So,

We also know that f(x) goes through the point (-4,8)... Set up the following:

Where b is our y-intercept, which we need to solve for:

Finally, put it all together:

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