Question

Let f (x) = x2 + 18x + 85.
(a) Find the vertex. Answer: ________
(b) State the range of the function. Answer: ________
(c) On what interval is the function decreasing? Answer: ________

Answer 1

f(x)=\[x ^{2}+18x+85\]
f(x)=\[(x+9)^2-81+85\]
\[f(x)=(x+9)^2+4\]
Vertex = (-9 , 4)
\[range = [4.\infty[\]
It decreases
\[x \in ]-\infty,-9]\]

Answer 2

Very good!