Answer:
1st
Vertex
we have
f(x)=x²-18x+88
let
y=x²-18x+88
comparing above equation with ax²+bx+c
we get
a=1
b=-18
c=88
now
vertex(x,y)=(-b/2a,f(-b/2a))
x=(18/2×1)=9
y=f(9)=9²-18×9+88=7
SO
VERTEX(X,Y)=(9,7)
=
Why did you post this then?
X + 1/4x = 15
4/4x + 1/4x = 15
5/4x = 15
5x = 60
x = 12