Applications of the Focus Point.
1. Two pairs of data,
$(1,2)$ and  $(2,0)$determine a linear function, $f$.
Find $f(0)$.

Solution: Draw the arrows on the Mapping Diagram and extend them if needed to meet at the Focus Point.
To find $f(0)$
on the MD, draw the line from the focus point through $0$ on the Domain Axis . Where the line meets the Target Axis is $f(0)$.

2. Using the same function as in the previous problem find $a$ where $f(a)= 1$.
Solution: Draw the line from the focus point of $f$ to $1$ on the Target Axis. Where this line meets the Domain Axis, is the desired value for $a$.

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