9x² + 12x + 4 = 10 + 3(x² - 4)
9x² + 12x + 4 = 10 + 3x² - 12
9x² - 3x² + 12x + 4 + 2 =0
3x² + 12x + 6 =0 ( сокращаем на 3)
x² + 4x + 2 = 0
D = b² -4ac = 16 - 4×2 = 16 - 8 = 8
x1 = ( - 4 + 2√2) / 2 = - 2( 2 - √2) /2 = - (2 - √2) = √2 - 2
x2 = ( -4 - 2√2) / 2 = - 2( 2 + √2) / 2 = - ( 2 + √2) = - √2 - 2