Tables
Tables
Tables
Example 3
Find the equation that models this table in vertex form. 

x  | -2  | -1  | 0  | 1  | 2  | 3  | 4  | 
y  | 12  | 9  | 7  | 6  | 6  | 7  | 9  | 
Step 1 . Find the second difference.
x  | -2  | -1  | 0  | 1  | 2  | 3  | 4  | 
y  | 12  | 9  | 7  | 6  | 6  | 7  | 9  | 

Step 2. Find the a-value.
The a-value is found by dividing the second difference by 2.
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Step 3. Find the h-value.
The h-value is the x-coordinate of the vertex. Due to symmetry, the x-coordinate of the vertex is 1.5. Therefore, h = 1.5.
Step 4. Find the k-value.
Substitute a and h into the equation and solve for k.

Step 5 . Substitute a, h and k into the equation.
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