\[(7y - 1)\left( y^{2} - 5y + 1 \right) =\]
\[= 7y^{3} - 35y^{2} + 7y - y^{2} + 5y - 1 =\]
\[= 7y^{3} - 36y^{2} + 12y - 1\text{.\ }\]