If n is a positive integer,is the value of b-a atleast twice the value of 3^n - 2^n ?
1. a = 2^(n+1) and b = 3^(n+1)
2. n = 3
1. a = 2^(n+1) and b = 3^(n+1)
2. n = 3
b-a=3^(n+1)-2^(n+1)= 3.3^n-2.2^n= 3^n+2.3^n-2.2^n=3^n+ 2(3^n-2^n)
a is sufficient
b is not sufficient
