## College Algebra 7th Edition

$2y^2(y^2+4)(y+2)(y-2)$
Factor out the GCF $2y^2$ to obtain: $=2y^2(y^4-16)$ Since $y^4=(y^2)^2$ and $16=4^2$, the expression above is equivalent to: $=2y^2[(y^2)^2-4^2]$ Factor the difference of two squares using the formula $a^2-b^2=(a+b)(a-b)$ where $a=y^2$ and $b=4$ to obtain: $=2y^2(y^2+4)(y^2-4) \\=2y^2(y^2+4)(y^2-2^2)$ Factor the difference of two squares with $a=y$ and $b=2$ to obtain: $=2y^2(y^2+4)(y+2)(y-2)$