Which equation represents a nonlinear function?

x(y – 5) = 2

y – 2(x + 9) = 0

3y + 6(2 – x) = 5

2(y + x) = 0

Set $r$ is a set of rectangles such that (1) only the grid points shown here are used as vertices, (2) all sides are vertical or horizontal and (3) no two rectangles in the set are congruent. if $r$ contains the maximum possible number of rectangles given these conditions, what fraction of the rectangles in set $r$ are squares? express your answer as a common fraction.

Awindow washer cleans 42 windows in 2 hours. at this rate, how many windows did he clean in 180 minutes.

What are the solutions of the equation x4 + 6x2 + 5 = 0? use u substitution to solve.