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What is the vertex of the quadratic function f(x) = (x – 8)(x + 2)?

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Answer:

The vertex is (3,-25)

Explanation:

Quadratic Function has the form:


f(x)=ax^2+bx+c

Lets use distributive property [a(b+c)=ab+ac] to make the equation given into the vertex form. Thus, we have:


f(x)=(x-8)(x+2)\\f(x)=x^2+2x-8x-16\\f(x)=x^2-6x-16

Thus,

a = 1

b = -6

c = -16

The x coordinate of vertex is given as:


x=-(b)/(2a)

Putting the points, we have:


x=-(-6)/(2(1))=3

Putting x = 3 into the function, we get y-value of vertex:


f(x)=(x-8)(x+2)\\f(x)=(3-8)(3+2)\\f(x)=(-5)(5)\\f(x)=-25

The vertex is (3,-25)

User Vlad Dinulescu
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