Constant of proportionality from equations problem what is the constant of proportionality in the equation y=2.5x

What is the product of the radical expression. (7-2square root) (8+2 square root)

Aschool puts on a play. the play costs $1,200 in expenses. the students charge $4.00 for tickets. there will be one performance of the play in an auditorium that seats 500 people. what is the domain of the function that shows the profit as a function of the number of tickets sold?  

If 2(a^2+b^2)=(a+b)^2 then, > a+b=0, > ab=0, > a=b, > 2a=b