Question

http://i68.tinypic.com/zyfxhi.jpg Can someone check if i am doing right? And also help ones with minus. (It is factoring of cube)

Answer 1

first is correct
second is correct
third is correct
-27-b^3=(-3)^3-b^3=(-3-b)*(9-3b+b^2)
-a^3-125=-a^3-5^3=(-a-5)*(a^2-5a+25)

Answer 2

So i just leave minus, right?:)

Answer 3

And + changes to - ??
In this part > (a^2-5a+25)