[ 2^(n+1)+3^(n+1)]/[2^n+3^n]
=[2*2^n+3*3^2]/[2^n+3^n]=[2*2^n+2*3^2+3^n]/[2^n+3^n]=2+3^n/[2^n+3^n]lim 2+1/[1+(2/3)^n]=3