Expand (y2−2y+7)(7y−3)(y2-2y+7)(7y-3) by multiplying each term in the first expression by each term in the second expression.y2(7y)+y2⋅−3+(−2y(7y)−2y⋅−3)+(7(7y)+7⋅−3)
Remove unnecessary parentheses.y2(7y)+y2⋅−3−2y(7y)−2y⋅−3+7(7y)+7⋅−3
Simplify each term:
7y3−3y2−14y2+6y+49y−21
=7y3−17y2+55y−21