Which of the following is not closed under the operation being performed ?

Areal estate agent earns $32,000 a year plus $1,000 for each apartment he sells. write an equation that shows the relationship between the number of apartments abe sells,n, and the total amount he earns in a year,e. what is the total amount abe would earn from selling 10 apartments in one year

What values of x satisfy the inequality x^2-9x< 0? how is your answer shown on the graph?

(x-5)1/2+5=2 what is a possible solution?