IXL | Write equations for lines of best fit

What is the equation of the trend line in the scatter plot?

Use the two blue points to write the equation in slope-intercept form. Write any coefficients as integers, proper fractions, or improper fractions in simplest form.

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Learn with an example

question

What is the equation of the trend line in the scatter plot?

Use the two yellow points to write the equation in slope-intercept form. Write any coefficients as integers, proper fractions, or improper fractions in simplest form.

key idea

A trend line roughly describes the relationship between two variables in a set of data. You can use a trend line to make predictions from a scatter plot.

solution

Step 1: Find the coordinates of the two yellow points.

Look at the two yellow points.

Their coordinates are

(

)

and

(

)

Step 2: Use the two points to find the slope.

Plug

(

)

and

(

)

into the slope formula.

change in

–

The slope is 3.

Step 3: Use the slope and a point to find the

-intercept.

Plug the slope

and a point such as

(

)

into the slope-intercept formula. Then solve for the

-intercept

Plug in

and

(

)

Plug in

and

Multiply

–

Subtract 15 from both sides

The

-intercept

–

Step 4: Use the slope and the

-intercept

to find the equation of the line.

Plug the slope

and the

-intercept

–

into the slope-intercept formula.

Plug in

and

–

Plug in

and

–

The equation of the trend line in slope-intercept form is

–

Looking for more? Try these:

Lesson: Line of best fit

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Teacher tools

Work it out

Not feeling ready yet? These can help:

II.8Identify lines of best fit

AA.9Write a linear equation from two points

Lesson: Line of best fit

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