#### Answer

$(13y^2+1)(13y^2-1)$

#### Work Step by Step

$\bf{\text{Solution Outline:}}$
To factor the given expression, $ 169y^4-1 ,$ use the factoring of the difference of $2$ squares.
$\bf{\text{Solution Details:}}$
Both $169y^4 \text{ and } 1$ are perfect squares (the square root is exact) and separated by a minus sign. Using the factoring of the difference of $2$ squares which is given by $a^2-b^2=(a+b)(a-b),$ the expression above is equivalent to \begin{array}{l}\require{cancel}
=(13y^2)^2-1^2
\\\\=
(13y^2+1)(13y^2-1) .\end{array}