I have a very basic doubt in the derivation of Electric Potention due to a charged disc. I got it by the normal dV=\frac{kdq}{x} method. But I tried to derive by using V=-\int_0^R{Edx} by using E=\frac{\sigma}{2\epsilon_0}[1-\frac{x}{ā(x^2+R^2)}] . Iām not getting the same result.

Can you guys try both the methods as well?