y=2(x²+18x+85)
Find the vertex of x²+18x+85
This is written of the form ax²+bx+c
a=1, b=18, c=85
The axis of symmetry is -b/2a
The axis of symmetry is the x term of your vertex (h,k)
So we have
h=-(18)/2
h=-9
k=f(-9) given that f(x) is x²+18x+85
(-9)²+18(-9)+85
81-162+85
-81+85
4
So your k value is 4
So because you’re vertex is (h,k) and since we found that h=-9 and k=4, your vertex is (-9,4)