Hi I am having a few problems with a couple of questions of an algebra revision assignment. I have never heard of, nor been taught how to do the sum of two cubes up until this point.

a) 54x^3 +2

b) x^6 -7x^3 -8

I have been having a go with the first one as it seems simpler. Using the theory I have found on wikipedia . a^3 + b^3 = (a+b)(a^2 -2ab + b^2) I have tried to *fudge* an answer but it isnt working out when I expand it to check my work.

a) 2(27x^3 +1)

2(1+3x)(9x^2 -6y+1)

This is where I come to trying to jam it into a formula, however through not knowing what to do or making a blind mistake it doesnt seem to be correct.

I have no idea where to start with the second problem, seeing as I cannot do a much easier question. Any help is much appreciated