4x^2 - 12x + 9 = 0
2) (2x - 3)^2 = 0
2x - 3 = 0
2x= 3
x = 1.5
3) x^2 + 2x - 24 = 0
По теореме Виета
x1 + x2 = -2
x1*x2 = -24
4 - 6 = -2
4*(-6) = -24
x1 = 4
x2 = -6
5) x^2 - 7ax + 12a^2 = 0
По теореме Виета
x1 + x2 = 7a
x1 * x2 = 12a^2
3a + 4a = 7a
3a * 4a = 12a^2
x1 = 3a
x2 = 4a
6) x^2 + 5bx + 6b^2 = 0
По теореме Виета
x1 + x2 = -5b
x1 * x2 = 6b^2
-2b - 3b = -5b
-2b * (-3b) = 6b^2
x1 = -2b
x2 = -3b
8) x^2 + (V2 + V6)x + 2V3 = 0
По теореме Виета
x1 + x2 = -V2 - V6
x1 * x2 = 2V3
-V2 - V6 = -V2 - V6
(-V2)*(-V6) = 2V3
x1 = -V2
x2 = -V6