How do I use the vertex formula to determine the vertex of the graph for $y=-x^2+4x+12$ ?

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Answer 1 · 2018-05-16T05:15:33

(2,16) is the maximum

$(-b)/(2a)$ gives you the x coordinate at the vertex

$(-4)/(2 xx -1)=(-4)/(-2)=2$

If x=2, $y=-2^2+4xx2+12=> y=16$

(2,16) is the vertex

Answer 2 · 2018-05-16T05:18:52

The vertix $(x_v,y_v)=(2,16)$

$y=ax^2+bx+c$

$x_v=-b/(2a)$

$y_v=a(x_v)^2+b(x_v)+c$

$y=-x^2+4x+12$

$x_v=-4/(-2)=2$

$y_v=-(2)^2+4(2)+12=-4+8+12=16$

The vertix $(x_v,y_v)=(2,16)$

How do I use the vertex formula to determine the vertex of the graph for y=-x^2+4x+12y=-x^2+4x+12?