Question

An algebra tile configuration. Only the Product spot is shown. 15 tiles are in the Product spot in 6 columns with 6 rows. First row: 1 + x squared, 5 negative x. Below the + x squared tile are 5 negative x tiles. Off to the right are 4 negative tiles in a separate column.
How many zero pairs must be added to the function
f(x) = x2 – 10x – 4 in order to begin writing the function in vertex form?

4
10
21
25

Answer 1

25

Explanation: To complete the square for x^2 − 10x you need to add (10/2)^2 = 25. You add +25 and −25 (a net zero) to keep the function equivalent — that is 25 zero pairs (25 copies of +1 and −1).