I'm taking a grade $11$ summer school math course right now and I'm having trouble with the functions unit that we're on. I've been having a hard time understanding this question. I'm pretty bad at math so all of these math terms aren't really sticking to my head. I've tried reading over the content my teacher has provided and the google meet session he holds but I'm still not really getting it.
A large greenhouse is to be built and subdivided into $6$ rectangular areas as shown. A rectangle is subdivided into a $2\times3$ grid. The building budget allows for a total $600$ meters of walls. This results in the following quadratic model between the total area $A$, in square meters, and length, $l$ meters, of the greenhouse: $A = -0.75l^2+ 150l$.
a) Find the zeros of this relation. Interpret the meaning of the zeros in the context of this question.
b) What length results in the greatest possible area? What is this area?
By zeros, it means the values at which $A(l) = 0$. If you have studied quadratic equations at all, try to solve this.
Hint : Completing the square will be very useful here.