3^100 - 3^99 + 3^98 - 3^97 + ......+ 3^2 + 3^1 + 1

We can rewrite the given expression as:
\[3^{100} + (-3^{99} + 3^{99}) + (-3^{98} + 3^{98}) + \ldots + (-3^2 + 3^2) + (-3^1 + 3^1) + 1\]
Notice that all the terms in parentheses cancel out, leaving us with:
\[3^{100} + 1\]