@Estevao Teixeira Thank you for your reply.
Is it because of this type of equation? because for every other type of equation I tried, it seems that the step-by-step solution does works.
Additionally, the link you shared when using "y" instead of "f(x)" have a step-by-step solution with a 1 single step, which is not really helps to understand how to solve this kind of equation.
What I'm looking for is the process explanation of how did WolframAlpha reached the conclusion that the solution of this equation is y=0 and y=3.