We have 2470 students and the ratio of students to teachers is 26:1. This means that for every teacher, there are 26 students. Put another way, we can set up this ratio
2470/x = 26/1
where x is the number of teachers. Cross multiply and solve for x
F(x)=x(3x+5) or f(x)=3x²+5x Here the domain in general is: -∞<x<∞ But the length of the rectangle cannot be negative, therefore the domain is all real numbers greater than zero.