IXL | Write a linear function from a table

Fill in the missing number to complete the linear equation that gives the rule for this table.

x	y
5	86
6	87
7	88
8	89

y = x +

ref_doc_title.

Learn with an example

question

Which equation gives the rule for this table?

x	y
5	^–55
6	^–66
7	^–77
8	^–88

y = ^–11x − 4

y = ^–11x − 6

y = ^–11x − 1

y = ^–11x

key idea

Linear functions are of the form y = mx + b.

solution

First find m. Look at the table and notice that every time the x terms go up by 1, the y terms go down by 11. This means that m is equal to ^-11.

x	y
5	^–55
6	^–66
7	^–77
8	^–88

Next find b. Take the equation y = mx + b and plug in the m value (m = ^-11) and a pair of (x, y) coordinates from the table, such as (5, ^–55). Then solve for b.

mx + b

Plug in m = ^-11, x = 5, and y = ^-55

^–55

^–11(5) + b

Plug in m = ^-11, x = 5, and y = ^-55

Simplify

^–55

^–55 + b

Simplify

Finally, use the m and b values you found (m = -11 and b = 0) to write the equation.

mx + b

Plug in m = ^-11 and b = 0

^–11x + 0

Plug in m = ^-11 and b = 0

Simplify

^–11x

Simplify

Now check your answer. Plug in each (x, y) pair in the table, and see if the result is a true statement.

Plug in (5, ^-55).

^–11x

^–55

^–11(5)

^–55

Plug in (6, ^-66).

^–11x

^–66

^–11(6)

^–66

Plug in (7, ^-77).

^–11x

^–77

^–11(7)

^–77

Plug in (8, ^-88).

^–11x

^–88

^–11(8)

^–88

Each (x, y) pair from the table resulted in a true statement.

So, the equation is y = ^–11x.

Looking for more? Try these:

Lesson: Linear functions

Lesson: Slope

$Confetti$

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Teacher tools

Work it out

Not feeling ready yet? These can help:

AA.9Write a linear equation from two points

Z.3Find the slope from a table

Lesson: Linear functions

Lesson: Slope

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