Problem 1: I need to use induction to prove that the number of binary strings of length n equals 2^n.

Problem 2. Number of binary strings of length at most n equals 2^(n+1) -1

Problem 3. for every integer n > 0 or n = 0 there are integers a and b such that 2a + 3b = n.

Can somebody help me out on these 3 problems, they are my last posts as i finish my course tomorrow! It be great help if you guys can show me these 3 questions cause they will be in exam i bet!

Thanks!