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

Question

1688 views around the world

You can reuse this answer
Creative Commons License

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)#