Answer: 9
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Explanation:
Recall the standard form of a quadratic is ax^2+bx+c
The 'b' is the coefficient of the x term. In this case, b = -6
Cutting that in half yields b/2 = -6/2 = -3
Then squaring that result gets us (b/2)^2 = (-3)^2 = 9
We must add 9 to both sides to complete the square.
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Extra info (optional section):
If we added 9 to both sides, we could then say the following
1 = x^2 - 6x
1+9 = x^2 - 6x + 9
10 = (x - 3)^2
(x-3)^2 = 10
Which would be useful to apply the square root rule to help isolate x.
