Question

[9.01] What is the vertex for the graph of y = −3x^2 + 18x − 13?

Answer 1

for finding vertex suggest you several ways:
suppose you have Eq:ax^2 + bx + c
then the x of vortex = (-b)/2a
and you can find y by substituition.
2.you can derivate the Eq and put it equal to zero
then you can find the x and y.
if you need more clear answer im here.