ok i dont know how to write square root so '\' means 'square root'

Q1. Differentiate by using the Chain Rule

f(x)=\2x-1

Square root of 2x-1

Q2. Differentiate by First Principals

f(x)=\2x-1

I already know that the answers should be the same but i cant work it out using first principals and keep ending up with f'(x)=1