Ta có:
\(S=3^0+3^2+3^4+...+3^{2002}\)
\(3^2S=3^2+3^4+...+3^{2004}\)
\(9S-S=\left(3^2+3^4+3^6+...+3^{2004}\right)-\left(3^0+3^2+3^4+...+3^{2002}\right)\)
\(8S=3^{2004}-3^0\)
\(8S-3^{2004}=-1\)
\(8S-3^{2004}-1=-2\)
Vậy \(8S-3^{2004}-1=-2\)
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S = 30 + 32 + 34 + ... + 32002
32S = 32 + 34 + 36 + .... +32004
9S - S = 32 + 34 + 36 + ... +32004 - 30 - 32 - ... - 32002
8S = 32004 - 30 = 32004 - 1
=> 8S - 32004 - 1 = 32004 - 1 - 32004 - 1 = -2
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