The functions f(x) = –(x + 4)2 + 2 and g(x) = (x − 2)2 − 2 have been rewritten using the completing-the-square method. Is the vertex for each function a minimum or a maximum? Explain your reasoning for each function.

Respuesta :

The vertex form of a quadratic function:

(h,k) - the coordinates of the vertex

If a>0, then the parabola opens upwards, so the vertex is the minimum of the function.
If a<0, then the parabola opens downwards, so the vertex is the maximum of the function.

 

F(x) = (x+4)^2+2

A = -1 <0

 Vertex is a maximum

 

G(x) = (x-2)^2-2

A = 1>0

Vertex is a minimum


Answer:

vertex of f(x) is the maximum point.

vertex of g(x) is the minimum point.

Step-by-step explanation:

The given functions are

[tex]f(x)=-(x+4)^2+2\\\\g(x)=(x-2)^2-2[/tex]

These represents parabola. The vertex form of a parabola is given by

[tex]y=a(x-h)^2+k[/tex]

Here, (h,k) is the vertex of the parabola.

Now, the parameter 'a' decides the shape of the parabola.

  • if a > 0 then parabola will be upward and vertex is the minimum point
  • If a < 0 then parabola will be downward and vertex is the maximum point

For the function f(x), a =- 1 and vertex is (-4,2). Since a < 0 hence, parabola opens downward and vertex will be the maximum point.

For the function g(x), a= 1  and vertex is (2,-2). Since a > 0 hence, parabola opens upward and vertex will be the minimum point.