First, what is common between our 3 terms? Interestingly, 3.
27m2 - 36m + 12 = 3(9m2 - 12m + 4)
Can we factor our trinomial? I'll show you a way that I learned.
9 x 4 = 36
What two factors of 36 have a sum of -12? How about -6 and -6?
3(9m2 - 12m + 36) = 3(9m2 - 6m -6m + 4)
Now, what do the first two terms have in common? 3m.
9m2 - 6m = 3m(3m - 2)
Now, the last two terms have -2 in common.
-6m + 4 = -2(3m - 2)
Soooooo...
3(9m2 -12m + 4) = 3(3m(3m - 2) - 2(3m - 2))
Since 3m and -2 are multiplied by 3m - 2, we can add them, except that they are not like terms.
3(9m2 - 12m + 4) = 3((3m - 2)(3m - 2)) = 3(3m - 2)2