hi i need help with this question, i got some of it...

The volume of a cardboard box is Factor this polynomial.

i got (x-1)(x-5)(x-2)

if these factors represent the length, width, and height, find the demensions of a box that has a volume of

i got ...

i then found a factor of (x-6), and after putting that through senthetic division i was left with , but this dosent really factor, so i think i've done something wrong...help please