Why is cos(npie)=(-1)n true, when n could be any integer?

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.

Which of the following is the best first step in solving the equation below? 4+2㏒³x=17

Ab and bc are tangent to circle d. find x is ab = 3x + 8 and bc = 26. find x