Show that (x+y)² − (x −y)² = 4xy for all real numbers x and y.

Perry angelo is planning to open a restaurant. he has the resources to produce and sell either hamburgers or pizzas. so he does some research and finds that the new location has a good demand for pizza. he hires cooks, wait staff, and an accounts person for his new pizzeria. he also arranges for materials such as pizza ingredients and pizza boxes. determine three factors affecting perry's cost of making pizza. write down the name of the factors and their instances in this scenario.