Multiply $\frac{\left(a^{2}-1\right)\left(a^{2}+1\right)}{aa}$ times $\frac{a^{4}+1}{a^{2}}$ by multiplying numerator times numerator and denominator times denominator.
Consider $\left(a^{4}-1\right)\left(a^{4}+1\right)$. Multiplication can be transformed into difference of squares using the rule: $\left(a-b\right)\left(a+b\right)=a^{2}-b^{2}$. Square $1$.
$$\frac{\left(a^{4}\right)^{2}-1}{a^{4}}$$
To raise a power to another power, multiply the exponents. Multiply $4$ and $2$ to get $8$.
Multiply $\frac{\left(a^{2}-1\right)\left(a^{2}+1\right)}{aa}$ times $\frac{a^{4}+1}{a^{2}}$ by multiplying numerator times numerator and denominator times denominator.
Consider $\left(a^{4}-1\right)\left(a^{4}+1\right)$. Multiplication can be transformed into difference of squares using the rule: $\left(a-b\right)\left(a+b\right)=a^{2}-b^{2}$. Square $1$.
$$\frac{\left(a^{4}\right)^{2}-1}{a^{4}}$$
To raise a power to another power, multiply the exponents. Multiply $4$ and $2$ to get $8$.