1)y^2+y-12/y^2+8y+16
y^2+4y-3y-12/(y+4)^2
y (y+4)-3(y+4)/(y+4)^2
(y-3)(y+4)/(y+4)^2
y-3/y+4
2)4m^2+12m+9/2m^2-m-6
(2m+3)^2/2m^2+3m-4m-6
(2m+3)^2/m(2m+3)-2(2m+3)
(2m+3)^2/(m-2)(2m+3)
(2m+3)/m-2
3)a^3+a^2-a-1/a^2+2a+1
a^2*(a+1)-(a+1)/(a+1)^2
(a^2-1)(a+1)/(a+1)^2
(a-1)(a+1)(a+1)/(a+1)^2
(a-1)(a+1)^2/(a+1)^2
a-1