Please can you differentiate this equation with respect to q1.
c= 1
Here is the equation:
P1= (20q1)-(1/10q1^2)-(1/10q1q2)-(q1c)
Thanks
$\displaystyle P_1= 20q_1 - \frac{1}{10q_1^2} - \frac{1}{10q_1q_2} - q_1c$
$\displaystyle P_1= 20q_1 - 10q_1^{-2} - 10q_1^{-1}q_2^{-1} - q_1c$
You need you use
$\displaystyle y=x^n \Rightarrow \frac{dy}{dx}= nx^{n-1}$
treat $\displaystyle q_2$ as a constant