1.) Factor 9u^2-12u

2.) Cancel any common factors (in bold will be the terms eliminated)

Final answer is:
3u-4
Therefore, the answer is
C. 3u-4
Perfect square is
a²+2ab+b²
so just take the square root of the end ones and add then double to get middle term
A.
m+10=10m, doubled is 20m
nope
B.
m+5=5m, doubled is 10m, yep
C.
m+2√15=fancy thing that won't get to 36m
D.
m+12=12m, doubled is 24m, yep
B and D
i need more info. Is this the whole question?