Use completing the square to find the minimum of y = x^2 - 4x + 8
Remember completing the square gives a result of the form (x+q)2 + p where q and p are numbers
Also q is always half of the x term, which in this case is -4, as such q = -2
Substituting this in, we get (x-2)2 which expands to x2 - 4x + 4. To make this equal to our original equation, we need to add 4, getting us y = (x-2)2 + 4.
As a rule, the minimum point is always x = -q, y = p. Therefore our answer is (2,4)
SD
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