A square has a side that is 5 meters long. What is the diagonal length of the square?

How do you use the elimination method for this question? explain, because i really want to understand!

Plz determine whether the polynomial is a difference of squares and if it is, factor it. y2 – 196 is a difference of squares: (y + 14)2 is a difference of squares: (y – 14)2 is a difference of squares: (y + 14)(y – 14) is not a difference of squares

If the cost to mail a package is an initial $5 and $0.28 for every pound the total cost to mail a package was $11.27, how much did the package weigh?