For each expression listed, is it a difference of squares? Explain yes or no and why or why not. Explain in enough detail so there is no doubt that it is or isn't a difference of squares. Examples were completed in class as well as in Worked Examples in D2L. 1. y5 − 25 2. 9m2n2 − 121 3. p18 − q10 4. 16r2 − 27

You are standing next to a really big circular lake. you want to measure the diameter of the lake, but you don't want to have to swim across with a measuring tape! you decide to walk around the perimeter of the lake and measure its circumference, and find that it's 400\pi\text{ m}400? m. what is the diameter dd of the lake?