lim(n无穷大) [(2^3n - 3^(2n+1)]/(2^3n + 3^2n)
= lim(n无穷大) [(8^n - 3*9^n]/(8^n + 9^n)
= lim(n无穷大) [(8/9)^n - 3*(9/9)^n]/[(8/9)^n + (9/9)^n]
= lim(n无穷大) -3/1
= -3