I need help someone pls

How can you decide witch operations to use to slice a two step equation

Find the vertex of the function given below y=x^2-6x+1

Steve wants to develop a way to find the total cost of any item including sales tax. the sales tax in his city is 6%. his friend jenna writes the expression x + 6x where x is the cost of the item. explain whether her expression is correct based on the situation.