Find Vertex of Trinomial

[mathdad]

Find the vertex: -4x^2 + 16x - 7

Vertex = ( x, f(x)).

x = -b/2a

x = -16/2(-4)

x = -16/-8

x = 2

f(x) = -4x^2 + 16x - 7

Let x = 2

f(2) = -4(2)^2 + 16(2) - 7

f(2) = -4(4) + 32 - 7

f(2) = -16 + 32 - 7

f(2) = 16 - 7

f(2) = 9

Vertex = (2, 9)

Yes?

 

[MarkFL]

[MATH]f(x)=-4x^2+16x-7=-4(x^2-4x)-7=-4(x^2-4x+4)-7+16=-4(x-2)^2+9[/MATH]
Vertex is:

[MATH](2,9)\quad\checkmark[/MATH]