First, subtract color(red)(13) from each side of the equation to isolate the n term while keeping the equation balanced:
-color(red)(13) + 13 - 8n^2 = -color(red)(13) - 1139
0 - 8n^2 = -1152
-8n^2 = -1152
Next, divide each side of the equation by color(red)(-8) to isolate n^2 while keeping the equation balanced:
(-8n^2)/color(red)(-8) = (-1152)/color(red)(-8)
(color(red)(cancel(color(black)(-8)))n^2)/cancel(color(red)(-8)) = 144
n^2 = 144
Now, take the square root of each side of the equation to solve for x while keeping the equation balanced. Remember, the square root of a number produces both a positive and a negative result:
sqrt(n^2) = +-sqrt(144)
n = +-12
