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(Efomm 2022) O valor da soma \(1\cdot 2+2\cdot 3+3\cdot 4+\cdots +29\cdot 30\) é
\(C^2_{30}\)
\(2\cdot C^2_{30}\)
\(C^{29}_{31}\)
\(2\cdot C^{28}_{31}\)
\(C^3_{31}\)