3x(2)-6x-5 . (2)-квадрат . x=1+корень2

3x2 - 6x - 5 = 0
D = b2 - 4ac
D = 36 + 60 = 96 = (4√6)^2

x1,2 = -b ± √D/2a
x1 = 6 + 4√6/6 = 3 + 2√3/3
x2 = 6 - 4√6/6 = 3 - 2√6/3
ответ: x1 = 3 + 2√6/3
 ; x2 = 3 - 2√6/3

  x=1+КОРЕНЬ2

x=1+4

x=5 

3*(1+√2)^2-6*(1+√2)-5=3+6√2+6-6-6√2-5=-2

^2 - квадрат