Show that replacing k with k + 1 in 1 - 1/2^k gives an expression equivalent to 1 - 1/2^k + 1/2^(k+1)
1 - 1/ [2^(k + 1)] =
1 - 1 / [2^k * 2] =
1 - 1/2^k (1/2) =
1 + (-1/2)(1/2^k) = [notice that -1/2 = -1 + 1/2]
1 + [ -1 + 1/2] [ 1/2^k] =
1 - 1/2^k + (1/2)(1/2^k) =
1 - 1/2^k + 1 / [ 2^k *2] =
1 - 1/2^k + 1/ 2^(k + 1)
