\(B=\frac{-1}{3}+\frac{1}{3^2}-\frac{1}{3^3}+...+\frac{1}{3^{50}}-\frac{1}{3^{51}}\)
\(3B=-1+\frac{1}{3}-\frac{1}{3^2}+...+\frac{1}{3^{49}}-\frac{1}{3^{50}}\)
\(3B+B=\left(-1+\frac{1}{3}-...-\frac{1}{3^{50}}\right)+\left(-\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^{50}}-\frac{1}{3^{51}}\right)\)
\(4B=-1-\frac{1}{3^{51}}\)
\(B=\frac{-1-\frac{1}{3^{51}}}{4}\)
hok tốt!!
Tính \(1\frac{1}{2}+2\frac{2}{3}+3\frac{3}{4}+4\frac{4}{5}+...+50\frac{50}{51}+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{51}\)
Tính: \(1\frac{1}{2}+2\frac{2}{3}+3\frac{3}{4}+...+50\frac{50}{51}+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{51}\)= ________?
Tính B=\(-\frac{1}{3}+\frac{1}{3^2}-\frac{1}{3^3}+...+\frac{1}{3^{50}}-\frac{1}{3^{51}}\)
Tính: \(B=-\frac{1}{3}+\frac{1}{3^2}-\frac{1}{3^3}+...+\frac{1}{3^{50}}-\frac{1}{3^{51}}\)
Tính B= \(-\frac{1}{3}+\frac{1}{3^2}-\frac{1}{3^3}+...+\frac{1}{3^{50}}-\frac{1}{3^{51}}\)
TÍNH:
B=\(\frac{-1}{3}+\frac{1}{3^2}-\frac{1}{3^3}+...+\frac{1}{3^{50}}-\frac{1}{3^{51}}\)
Tính
B=\(-\frac{1}{3}+\frac{1}{3^2}-\frac{1}{3^3}+....+\frac{1}{3^{50}}-\frac{1}{3^{51}}\)
Tính bằng cách hợp lí:
\(B=\frac{-1}{3}+\frac{1}{3^2}-\frac{1}{3^3}+...+\frac{1}{3^{50}}-\frac{1}{3^{51}}\)
tính: \(-\frac{1}{3}+\frac{1}{3^2}-\frac{1}{^{3^3}}+.....+\frac{1}{3^{50}}-\frac{1}{3^{51}}\)
