tg²x-36tgx+68=0 пліз поможіть

tg^2x - 36tgx + 68 = 0 
tgx = y 
y^2 - 36y + 68 =0
a = 1 b = - 36 c = 68
D=b^2 - 4ac
D = 1296 - 272 = 1024 = 32^2 
x1.2 = (-b +/- D)/2a 
x1= 36 + 32/2 = 68/2 = 34
x2= 36-32/2 = 4/2 = 2
tgx=y
1) tgx = 34
x = arctg34  + Пn 
2) tgx = 2 
x = arctg2 + Пn