Finding Function Rules
Use input/output tables or graphs to find function rules
The first step when using an input/output table is finding the change in y values when the change in x is 1. Typically we want to see our input x values starting at 0 and increasing by 1 each step.
We can see that as x increases by 1, y increases by 4.
Now that we have this element we want to look at what the y-value is when x is zero.
In our example the y-value is 3
So our change in y is 4, and our starting point is 3
Now we need to put these elements together to create our function rule.
Creating our function
Where m is the change in y, and b is the starting point.
In our example our equation will look like:
Now try when the change in y is 8 and the starting point is 27.
WATCH THE VIDEO BELOW FOR STEP-BY-STEP INSTRUCTIONS ON HOW TO FIND A FUNCTION USING TWO POINTS IN AN INPUT AND OUTPUT TABLE