Im currently studying microeconomics and I have encountered a math problem which I can't seem to figure out. The concerned problem can be viewed in the image that I have posted. To be more specific, what I don't understand is how exactly the first order condition is derived. I know that I'm supposed to use the chain rule but when I do the calculations, my result is wrong. I guess that q1(1-q1-q2-c) is the outer function and 1-q1-q2-c is the inner function. Is that right? Can someone please take be through the steps to how I get 1-q1-q2-c-q1=0? I would be extremely thankful if someone could help me with this problem.
A confused student