IXL - Write a linear function from a table (Algebra 1 practice)

Which equation gives the rule for this table?

x	y
4	0
5	1
6	2
7	3

y = 5x − 4

y = 6x − 4

y = 4x − 4

y = x − 4

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Learn with an example

question

Which equation gives the rule for this table?

x	y
1	5
2	6
3	7
4	8

y = x + 4

y = x + 16

y = x + 35

y = x + 6

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 up by 1. This means that m is equal to 1.

x	y
1	5
2	6
3	7
4	8

Next find b. Take the equation y = mx + b and plug in the m value (m = 1) and a pair of (x, y) coordinates from the table, such as (1, 5). Then solve for b.

mx + b

Plug in m = 1, x = 1, and y = 5

1(1) + b

Plug in m = 1, x = 1, and y = 5

Simplify

1 + b

Simplify

Finally, use the m and b values you found (m = 1 and b = 4) to write the equation.

mx + b

Plug in m = 1 and b = 4

1x + 4

Plug in m = 1 and b = 4

Simplify

x + 4

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 (1, 5).

x + 4

1 + 4

Plug in (2, 6).

x + 4

2 + 4

Plug in (3, 7).

x + 4

3 + 4

Plug in (4, 8).

x + 4

4 + 4

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

So, the equation is y = x + 4.

Looking for more? Try these:

Lesson: Linear functions

Lesson: Slope

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Work it out

Not feeling ready yet? These can help:

AA.9Write a linear equation from two points

Lesson: Linear functions

Lesson: Slope

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