求大神！高中数学！求解求过程！
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(1)
a1 = 1
a2 = S2-a1 = 3/2
a3 = S3-S2 = 7/4
(2)
Suppose : an = 2 - (1/2)^(n-1)
n=1
a1= 1
p(1) is true
Assume p(k) is true
ak = 2 - (1/2)^(k-1)
for n=k+1
a(k+1) = S(k+1) - Sk
= [2(k+1) - a(k+1)] -[ 2k -ak]
2a(k+1) = 2+ak
= 2+ ( 2-(1/2)^(k-1))
a(k+1) = 2- (1/2)^k
p(k+1) is true
By principle of MI, it is true for all n
a1 = 1
a2 = S2-a1 = 3/2
a3 = S3-S2 = 7/4
(2)
Suppose : an = 2 - (1/2)^(n-1)
n=1
a1= 1
p(1) is true
Assume p(k) is true
ak = 2 - (1/2)^(k-1)
for n=k+1
a(k+1) = S(k+1) - Sk
= [2(k+1) - a(k+1)] -[ 2k -ak]
2a(k+1) = 2+ak
= 2+ ( 2-(1/2)^(k-1))
a(k+1) = 2- (1/2)^k
p(k+1) is true
By principle of MI, it is true for all n
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