Reggie, to solve an equation means to find the value(s) of the variable that make that equation true.to solve the equation we need to leave only the x by one side of the "=" and move every other factor by the other side. and to be able to do that, the greatest
rule you should follow is: take every factor that is placed on the same same side of the equation as the x, together with the proper +,-,*, or /, and transfer it by the other side of =. By this I mean:

1. if u need to remove a root, you can transfer it by the other side of the = by making of the factor of the root a power ( vice versa, the power gets transferred by the other side as a root, with it as a factor)

2. If you need to remove a multiplying factor, you transfer it as a divisor on the other side of =, and vice versa

3. To remove an adding factor, you can simply subtract it to the other side of =, and vice versa

and adopting these rules to your specific question, we have:

(1-x)^2=4

according to 1, the power transforms in sqrt. (1-x)= sqrt4= -2, Or +2. (We consider both positive and negative roots)

we now have 1-x=2 And 1-x=-2

to eliminate one step to the solution, in both equations, we remember of what we told on 3. And transfer the -x fron the left side, to the right side, making of it +x, and move the numbers 2 and -2 to the left, changing their signs also in -2, and +2.v like
this we have

1-2=x And. 1-(-2)= 1+ (+2)= x.

so 1-2= -1=x. And. 3=x.

The two values we found above of x (x= -1, and x=3) that make the equation true, are the solution to that equation.