Answer
$\color{blue}{16y^3+42y^2-73y+21}$
Work Step by Step
Distribute each term of the binomial factor to trinomial factor to obtain:
$=8y(2y^2+7y-3) -7(2y^2+7y-3)$
Distribute $8y$ and $-7$ to obtain:
$=8y(2y^2)+8y(7y)-8y(3)-7(2y^2)-7(7y) - 7(-3)
\\=16y^3+56y^2-24y-14y^2-49y+21$
Combine like terms to obtain:
$=16y^3+(56y^2-14y^2)+(-24y-49y)+21
\\=16y^3+(56-14)y^2+(-24-49)y+21
\\=16y^3+42y^2+(-73)y+21
\\=\color{blue}{16y^3+42y^2-73y+21}$
