A)
12x-3x^3/6x+6 = 3x(4-x^2)/6(x+1) = 4x-x^3/2x+2
б)
y-3/y^2-6y+9 = y-3/(y-3)^2 = 1/(y-3)
y^2 - 6y + 9 = 0
y1 = 3
y 2 = 3
y^2 - 6y + 9 = (y-3)^2
в)
m^2-4/m^2+4m+4 = (m-2)(m+2)/(m+2)^2 = m-2/m+2
г)
n^2-n-1/n^4-n^3-n^2 = n^2-n-1/n^2(n^2-n-1) = 1/n^2
#2
4x^2 - 9/9-12x+4x^2 = 4x^2 - 9/4x^2-12x+9 =
= (2x-3)(2x+3)/(2x-3)^2 = 2x+3/2x-3