Answer
$$\left(d+5\right)\left(d-5\right)\left(c+3\right)\left(c-3\right)$$
Work Step by Step
Factoring the expression completely, we find:
$$ -9\left(d^2-25\right)+c^2\left(d^2-25\right) $$
Recognize the difference of squares:
$$\left(d^2-25\right)\left(c^2-9\right) \\ \left(d+5\right)\left(d-5\right)\left(c^2-9\right) \\ \left(d+5\right)\left(d-5\right)\left(c+3\right)\left(c-3\right)$$
