I am down to 5 out of 49 problems that I can't figure out. Help is very much appreciated. Thanks !

Factor

81a^6 - 3q^6

81a^6 - 3q^6

= 3(27a^6 - q^6) , now I am looking at a difference of cubes
= 3(3a^2 - q^2)(9a^4 + 3a^2q^2 + q^4)