Y = (-2*k^3+6*k^2+sqrt(k^8-12*k^7+64*k^6-198*k^5+448*k^4-636*k^3+369*k^2)-7*k-15)/((k^3-3*k^2+5*k-15)*(1+k))

1. (k-2)*(k^2+5)*(k^3-k^2+7*k+8)/(6*k*(k^2-3*k+8))
2. (k+2)*(k^2+5)*(k^3-5*k^2+13*k-8)/(6*k*(k^2-3*k+8))
3. k^3+3*k^2+11*k-3
4. k^2+2*k+9

1. (2*k^3-6*k^2+7*k+15-k*sqrt(k^6-12*k^5+64*k^4-198*k^3+448*k^2-636*k+369))/(-k^4+2*k^3-2*k^2+10*k+15)
2. (k^3+5*k+(-k^2+k)*sqrt(k^4-10*k^3+37*k^2-60*k+180)+30)/(-k^4+k^3+k^2+5*k+30)