How do you solve #x^2-4=0#?
The easiest way to solve this quadratic equation is to isolate
To do that, add
Taking the square roots of both sides of the equation will get you
Alternatively, you could recognize that you're dealing with the difference of two squares, for which you know that
#color(blue)(a^2 - b^2 = (a-b)(a+b)#
In your case, you would get
This equation equals zero if