how does 3x(x-4)+5=12

= x=6+sq rt 57-3 or x=6-sq rt 57/3

3 x^2 - 12 x - 7 = 0

x = [ 12 +/- sqrt(144+84) ] / 6

= [ 12 +/- sqrt(228) ] / 6

= [ 12 +/- 2 sqrt(57) / 6

= [ 6 +/- sqrt(57) ] / 3

Use PARENTHESES !!!~!!~!!!!!
I can not tell whsat is your numerator.