\(S=\dfrac{1}{6}+\dfrac{1}{12}+...+\dfrac{1}{600}+\dfrac{1}{650}\)
\(=\dfrac{1}{2\cdot3}+\dfrac{1}{3\cdot4}+...+\dfrac{1}{24\cdot25}+\dfrac{1}{25\cdot26}\)
\(=\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{24}-\dfrac{1}{25}+\dfrac{1}{25}-\dfrac{1}{26}\)
\(=\dfrac{1}{2}-\dfrac{1}{26}=\dfrac{13-1}{26}=\dfrac{12}{26}=\dfrac{6}{13}\)
Tính tổng s= 1/6+ 1/12+ 1/20+ ........+ 1/90
tính tổng S= 1/6+1/12+1/20+1/30+1/42+1/56
tính tổng :
\(S=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{45.46}\)
tính dãy số sau
\(\frac{1}{2}\)+\(\frac{1}{6}\)+\(\frac{1}{12}\)+\(\frac{1}{20}\)+.........+\(\frac{1}{650}\)
giúp mk nhé
Tính tổng: 1/6 + 1/12 + 1/20 + 1/30 + 1/42.
Tính tổng:
S= 1/2 + 1/6 + 1/12 + ...+ 1/90
Tính tổng:
A=1/6+1/12+1/20+...+1/870.
TÍNH TỔNG
S=1/2+5/6+11/12+19/20+41/42+55/56+71/72+89/90
`D=(1-1/2)+(1-1/6)+(1-1/12)+...+(1-1/650)`
