Tính tổng S=C 0 n +(2^2-1)/2C 1 n+(2^3-1)/2C 2 n46/50Tính tổng S=Cn0+22-12Cn1+23-13Cn2+...+2n+1-1n+1Cnn3n+2-2n+2n+23n+1-2n+1n+13n+2+2n+2n+23n+1+2n+1n+1Giải thích
