[tex]\it \left(\dfrac{y}{2}-4z\right)^3 = \left(\dfrac{y}{2}\right)^3-3\left(\dfrac{y}{2}\right)^2\cdot4z +3\cdot\dfrac{y}{2}\cdot(4z)^2 -(4z)^3=
\\\;\\ \\\;\\
=\dfrac{\ y^3}{8}-3\cdot\dfrac{\ y^2}{4}\cdot4z+3\cdot\dfrac{y}{2}\cdot16z^2-64z^3=\dfrac{\ y^3}{8} -3y^2 z+24yz^2-
\\\;\\ \\\;\\
-64z^3.[/tex]