√(12х²-4) = 6х - 4,
( √(12х²-4) )² = (6х - 4)²,
12х² - 4 = 36х² - 48х + 16,
36х² - 12х² - 48х + 16 + 4 = 0,
24х² - 48х + 20 = 0,
6х² - 12х + 5 = 0,
Д = (-12)² - 4*6*5 = 144 - 120 = 24,
х1 = (12 + √24)/2*6 = (12 + 4√1,5)/12 = 1 + (√1,5)/3,
х2 = (12 - √24)/2*6 = (12 - 4√1,5)/12 = 1 - (√1,5)/3,