We need to add 6 to complete squares.
What must be added to complete the square?
Here we have the expression:
x^2 + 8x + 10
By looking at the image, we can see that we need to add 6 cubes of the ones with the digit 1.
That is equivalent to adding 6 to our expression (and we also subtract 6 so we don't change it) then we have:
x^2 + 8x + 10 + 6 - 6
(x^2 + 8x + 10 + 6) - 6
(x^2 + 8x + 16) - 6
(x^2 + 2*4*x + 4^2) - 6
(x + 4)^2 - 6
So we completed squares, then we conclude that we need to add 6 to complete squares.
If you want to learn more about completing squares, you can read:
https://brainly.com/question/10449635
