Question

How do you factor `-s^6 + 16s^4`?

Answer 1

`-s^6+16s^4 = -s^4(s^2-16) = -s^4(s^2-4^2)`

`= -s^4(s-4)(s+4)`

...using the difference of squares identity:

`a^2-b^2 = (a-b)(a+b)`