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Writing an Equation to Describe a Table - Concept 21,450 views

Teacher/Instructor Alissa Fong
Alissa Fong

MA, Stanford University
Teaching in the San Francisco Bay Area


In Algebra, sometimes we are given points and asked to write an equation to describe them. There are many methods we can use for writing an equation to describe a table. For example, if the table describes a line, we use the y-intercept and calculate the slope to write the equation. To fully understand this concept, students should know how to plot points and how to interpret graphs.

One of the most important skills in an Algebra class is to be able to be given a bunch of numbers in a relationship and to be able to write the function that describes those numbers. A lot of times you're given a table, sometimes pictures, sometimes a graph and you're asked to write the equation. What I want to show you guys today are some strategies for how you can tell what the equation would be if you are given a table. A table meaning like a group of x numbers and the corresponding y numbers. Couple of things to keep in mind when you're told it's a linear function or a line, try to remember your y=mx+b strategies keeping in mind that b represents the y intercept for juts when x is zero. That's one thing that's going to help you, and another thing that's going to be helpful for you is if you can look for the change in the table.
If you guys know about slope, you can use your slope techniques, if you don't know about slope you can still do these kinds of problems by looking for patterns. So what I want you guys to keep in mind is looking for that y intercept which is what happens when x is zero. And also looking for patterns in the change of the both x's and the y's.