How do you write the quadratic $F(x)=x^2-4x+9$ in vertex form?

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Answer 1 · 2015-05-19T13:46:37

Formula for vertex form: $F(x) = a(-b/2a)^2 + f(-b/2a)$

x of vertex: $x = -b/2a = 4/2 = 2$
y of vertex: $y = f(2) = 4 - 8 + 9 = 5$

Vertex form: $F(x) = (x - 2)^2 + 5.$

Check by developing: $F(x) = (x^2 - 4x + 4) + 5 = x^2 - 4x + 9.$ OK

How do you write the quadratic F(x)=x^2-4x+9F(x)=x^2-4x+9 in vertex form?