9514 1404 393
Answer:
4
Step-by-step explanation:
The square of a binomial is ...
(x -a)^2 = x^2 -2ax +a^2
The constant (a^2) is the square of half the x-coefficient: (-2a/2)^2 = a^2.
The missing constant is the square of half of -4, so is (-4/2)^2 = (-2)^2 = 4..
The missing constant is 4.
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Additional comment
You can probably see that the constant will always be positive here, so the sign of the x-term can be ignored. We only need to square half the magnitude.
