First, add #color(red)(2)# to each side of the equation to isolate the #x^2# term while keeping the equation balanced:
#2x^2 - 2 + color(red)(2) = 6 + color(red)(2)#
#2x^2 - 0 = 8#
#2x^2 = 8#
Next, divide each side of the equation by #color(red)(2)# to isolate #x^2# while keeping the equation balanced:
#(2x^2)/color(red)(2) = 8/color(red)(2)#
#(color(red)(cancel(color(black)(2)))x^2)/cancel(color(red)(2)) = 4#
#x^2 = 4#
Now, take the square root of each side of the equation to solve for #x# while keeping the equation balanced. Remember, when taking the square root of the number there are two solutions, one negative and one positive:
#sqrt(x^2) = +-sqrt(4)#
#x = +-sqrt(4) = +-2#