# What is the standard form of  y(8y + 5)(8y - 5) ?

Dec 8, 2016

64y^3 - 25y

#### Explanation:

First, cross multiply the terms in parenthesis:

$y \left(\left(8 y \cdot 8 y\right) - \left(5 \cdot 8 y\right) + \left(5 \cdot 8 y\right) - \left(5 \cdot 5\right)\right)$

y(64y^2 - 40y + 40y - 25#

$y \left(64 {y}^{2} - 25\right)$

Then distribute across the terms in parenthesis:

$64 {y}^{2} y - 25 \cdot y$

$64 {y}^{3} - 25 y$