Factor

81-(3t+2)(3t+2)

81-9t^2-6t-6t-4 =

81-9t^2-12t-4 =
-9t^2-12t+77
Use AC Method of factoring:
A*C = -9*77 = -693 = 3*-231 = 21*-33.
Use the part whose sum equals -12, the
coefficient of B:
21, and -33.
-9t^2+(21t-33t)+77
Divide the 4 terms into 2 factorable
binomials:
(-9t^2+21t) + (-33t+77) =
-3t(3t-7) - 11(3t-7)=
(3t-7)(-3t-11).