Answer :
Given:
A quadratic function has x-intercepts 2 and 6 and its vertex is (4, 8).
To find:
The corresponding quadratic expression.
Solution:
If graph of a function intersect the x-axis at c, then (x-c) is a factor of the function.
A quadratic function has x-intercepts 2 and 6. It means (x-2) and (x-6) are two factors of the required quadratic function.
The function is defined as:
[tex]P(x)=a(x-2)(x-6)[/tex] ...(i)
Where, a is a constant.
The vertex of the quadratic function is (4,8). It means the point (4,8) will satisfy the function.
Substituting x=4 and P(x)=8 in (i).
[tex]8=a(4-2)(4-6)[/tex]
[tex]8=a(2)(-2)[/tex]
[tex]8=-4a[/tex]
Divide both sides by -4.
[tex]\dfrac{8}{-4}=a[/tex]
[tex]-2=a[/tex]
Putting [tex]a=-2[/tex] in (i), we get
[tex]P(x)=-2(x-2)(x-6)[/tex]
[tex]P(x)=-2(x^2-6x-2x+12)[/tex]
[tex]P(x)=-2(x^2-8x+12)[/tex]
[tex]P(x)=-2x^2+16x-24[/tex]
Therefore, the correct option is B.