Question

(-y to the power of 2 - 4y-8)-(-4y to the power of 2 -6 y +3)

Answer 1

(-y^2-4y-8)(-4y^2-6y+3)
=4y^4+6y^3-3y^2+16y^3+32y^2-12y+48y-24
Collect like terms:
=4y^2+22y^3+53y^2+36y-24
That is the answer
I hope this is what you meant