Find dW/dd then use bisection or regula falsi to find the value of d that maximizes W

F = 2+(1/(1+exp(5*(0.8-d))));

C = 0.32*(1/(1+exp(10*(1-d))));

S = 2/(1+exp(0.5*(4+F)));

W = (1-C)*(1-S);

disp(diff(W,d))

I want the derivative of W in terms of d. It also says to use bisection or regula falsi to find the value of d between 0 and 1 that maximizes W.