4x^2 = 4
4x^2 - 4 = 0
4(x^2 - 1) = 0
x^2 - 1 = 0/4
x^2 - 1 = 0
(x-1)(x+1) = 0 <<--- use the difference of squares rule
x-1 = 0 or x+1 = 0
x = 1 or x = -1
The roots are x = 1 or x = -1
Note: "Root" is another term for "solution" or "zero" of a function
If we replace x with 1 or -1 back in the original equation, it leads to a true equation.