1)
xy+2y-2x-4
y•(x+2)-2(x+2)
otvet: (x+2)•(y-2)
2)
2cx-cy-6x+3y
(2x-2)•(c-3)
oyvet: (2x-y)•(c-3)
3)
2*(-1.5a - 2.8) + 4.2a - 6 = -3a - 5.6 + 4.2a - 6 = 1.2a - 11.6
a=-3/4
1.2 * (-3/4) - 11.6 = -0.9 - 11.6 = -12.5