Answer
$(d-5)^2$.
Work Step by Step
The given polynomial is
$=d^2-10d+25$
Write the the polynomial as $a^2-2ab+b^2$.
$=d^2-2(d)(5)+5^2$.
Use perfect square trinomial pattern
$a^2-2ab+b^2=(a-b)^2$.
We have $a=d$ and $b=5$.
$=(d-5)^2$.
Hence, the factor of the given polynomial is $(d-5)^2$.
