Answer:
[tex]24y^4-96y^3+133y^2-57y-10[/tex]
Step-by-step explanation:
Given expression
[tex](-8y^2+6y-1)+(-8y^2+8y+1)(-3y^2+9y-9)[/tex]
First, multiply two polynomials in brackets:
[tex](-8y^2+8y+1)(-3y^2+9y-9)\\ \\=24y^4-72y^3+72y^2-24y^3+72y^2-72y-3y^2+9y-9\\ \\=24y^4-96y^3+141y^2-63y-9[/tex]
No add two polynomials:
[tex]-8y^2+6y-1+24y^4-96y^3+141y^2-63y-9\\ \\=24y^4-96y^3+133y^2-57y-10[/tex]
