To factor 3u^2 - 108, do I divide 108 by 3?

Yes, and when you do, you get

3( u^2 - 36), which simplifies to 3(u+6)(u-6)

(3u² - 108)/3 = u² - 36
(u² - 36)/(u + 6) = u - 6

Answer: 3(u + 6)(u - 6) are the factors of u² - 108

Check (u = - 6):
3u² = 108
3(- 6²) = 108
3(36) = 108
108 = 108

Yes, 3 is the common factor so that is your first step.
3(u^2-36)
Then factor the second part because it is the difference of perfect squares.
3(u-6)(u+6)

3u^2 - 108
= 3(u^2 - 36)
= 3(u + 6)(u - 6)

pls gimme the exact qtn...
dunno wat ur askin. thnx

3 ( u ² - 36 )
3 ( u - 6 ) ( u + 6 )