Hey all. I have a question regarding an equation in a document I am reading about convex optimization of OP-AMPs. The document is attached, the equation is of section 3.4 and the equation number is (9). Can you please explain how it came to be? I understand that i3 = i4 = i5/2 but I don't understand why W's and L's are the only thing in this equation and why this equality holds. An explanation for equation (10) would also be nice, but (9) is more important for me! Thank you for your time.