Algebra 1 : Slope and Line Equations

Study concepts, example questions & explanations for Algebra 1

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Example Questions

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

Which of these lines has a slope ofand a-intercept of?

Possible Answers:

None of the other answers

Correct answer:

Explanation:

When a line is in theform, theis its slope and theis its-intercept. Thus, the only line with a slope ofand a-intercept ofis

.

Example Question #3631 :Algebra 1

What is the equation of a line with a slope of 3 that runs through the point (4,9)?

Possible Answers:

None of the other answers

Correct answer:

Explanation:

You can find the equation by plugging in all of the information to theformula.

The slope (or) is 3. So, the equation is now.

You are also given a point on the line: (4,9), which you can plug into the equation:

Solve forto get.

Now that you have theand, you can determine that the equation of the line is.

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

What is the equation of the line passing through the points (1,2) and (3,1) ?

Possible Answers:

Correct answer:

Explanation:

First find the slope of the 2 points:

Then use the slope and one of the points to find the y-intercept:

So the final equation is

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

What is the slope and y-intercept of?

Possible Answers:

Slope:; y-intercept:

Slope:; y-intercept:

None of the other answers

Slope:; y-intercept:

Slope:; y-intercept:

Correct answer:

Slope:; y-intercept:

Explanation:

The easiest way to determine the slope and y-intercept of a line is by rearranging its equation to theform. In this form, the slope is theand the y-intercept is the.

Rearranging

gives you

which has anof 2 and aof 6.

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

Find the equation of the line, inform, that contains the points,, and.

Possible Answers:

Correct answer:

Explanation:

When finding the equation of a line given two or more points, the first step is to find the slope of that line. We can use the slope equation,. Any combination of the three points can be used, but let's consider the first two points,and.

Sois our slope.

Now, we have the half-finished equation

and we can complete it by plugging in theandvalues of any point. Let's use.

Solving

forgives us

so

We now have our completed equation:

Example Question #16 :How To Find The Equation Of A Line

We have two points:and.

If these two points are connected by a straight line, find the equation describing this straight line.

Possible Answers:

None of these

Correct answer:

Explanation:

We need to find the equation of the line in slope-intercept form.

In this formula,is equal to the slope andis equal to the y-intercept.

To find this equation, first, we need to find the slope by using the formula for the slope between two point.

In the formula, the points areand. In our case, the points areand. Using our values allows us to solve for the slope.

We can replace the variablewith our new slope.

Next, we need to find the y-intercept. To find this intercept, we can pick one of our given points and use it in the formula.

Solve for.

Now, the final equation connecting the two points can be written using the new value for the y-intercept.

Example Question #17 :How To Find The Equation Of A Line

Which of these lines has a slope ofand a y-intercept of?

Possible Answers:

None of the other answers

Correct answer:

Explanation:

Since all of the answers are in theform, the slope of each line is indicated by itsand its y-intercept is indicated by its. Thus, a line with a slope ofand a y-intercept ofmust have an equation of.

Example Question #18 :How To Find The Equation Of A Line

Find the domain of:

Possible Answers:

Correct answer:

Explanation:

The expression under the radical must be. Hence

Solving for, we get

Example Question #19 :How To Find The Equation Of A Line

Give, in slope-intercept form, the equation of a line through the pointsand.

Possible Answers:

Correct answer:

Explanation:

First, use the slope formula to find the slope, setting.

We can write the equation in slope-intercept form as

.

Replace:

We can findby substituting forusing either point - we will choose:

The equation is.

Example Question #11 :Slope And Line Equations

Give, in slope-intercept form, the equation of a line through the pointsand.

Possible Answers:

Correct answer:

Explanation:

First, use the slope formula to find the slope, setting.

We can write the equation in slope-intercept form as

.

Replace:

We can findby substituting forusing either point - we will choose:

The equation is.

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