1) (х^2 + 3 х + 1) (х^2 + 3 х + 3) = - 1

2) (х^2 - 5) ^2 - 3 (х^2 - 5) - 4 = 0

1). x^2+3x+1=a. получаем: a * (a+2) = - 1; a^2+2a+1=0; D=2^2-4*1*1=0. a = (-2-0) / 2 = - 1. x^2+3x+1 = - 1; x^2+3x+2=0; D=3^2-4*1*2=1; x1 = (-3-1) / 2, x2 = (-3+1) / 2. x1 = - 2, x2 = - 1. Ответ: x1 = - 2, x2 = - 1. 2). x^2-5=a. a^2-3a-4=0; D = (-3) ^2-4*1 * (-4) = 9+16=25; a1 = (3-5) / 2, a2 = (3+5) / 2. a1 = - 1, a2=4. x^2-5 = - 1, x^2-4=0, (x-2) * (x+2) = 0, x-2=0 или x+2=0. x1=2, x2 = - 2. x^2-5=4, x^2-9=0, (x-3) * (x+3) = 0, x-3=0 или x+3=0. x3=3, x4 = - 3. Ответ: x1=2, x2 = - 2, x3=3, x4 = - 3.