First, add #color(red)(6)# to each side of the equation to isolate the #x# term while keeping the equation balanced:

#8n^2 - 6 + color(red)(6) = 306 + color(red)(6)#

#8n^2 - 0 = 312#

#8n^2 = 312#

Next, divide each side of the equation by #color(red)(8)# to isolate #x^2# while keeping the equation balanced:

#(8n^2)/color(red)(8) = 312/color(red)(8)#

#(color(red)(cancel(color(black)(8)))n^2)/cancel(color(red)(8)) = 39#

#n^2 = 39#

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 a number there is a negative and positive result:

#sqrt(n^2) = +-sqrt(39)#

#n = +-sqrt(39) = +-6.245# rounded to the nearest thousandth.