1) (5a+6)^2 - 81 = (5a+6+9)(5a+6-9) = (5a+15)(5a-3)2) 9m^2 - (1+2m)^2 = (3m+1)(3m-1-2m) = (3m+1)(m-1)3) (5c-3d)^2 - 9d^2 = (5c-3d+3d)(5c-3d-3d) = (5c)(5c-6d) = 5c(5c-6d)
1) (5a+6)^2 - 81 = (5a+6+9)(5a+6-9) = (5a+15)(5a-3)
2) 9m^2 - (1+2m)^2 = (3m+1)(3m-1-2m) = (3m+1)(m-1)
3) (5c-3d)^2 - 9d^2 = (5c-3d+3d)(5c-3d-3d) = (5c)(5c-6d) = 5c(5c-6d)