#### Answer

$(7y^2-5)(7y^2+5)$

#### Work Step by Step

RECALL:
A difference of two square can be factored using the formula
$a^2-b^2=(a-b)(a+b)$
The given binomial can be written as:
$=(7y^2)^2-5^2$
The binomial above is a difference of two squares.
Factor the difference of two squares using the formula above with $a=7y^2$ and $b=5$ to obtain:
$=(7y^2-5)(7y^2+5)$