\(B=\dfrac{1}{1.3}+\dfrac{1}{3.5}+\dfrac{1}{5.7}+...+\dfrac{1}{53.55}\)
`1/2B = (2/(2.3) + 2/(3.5) + 2/(5.7) + ... + 2/(53.55))`
`1/2B = (1 - 1/3 + 1/3 - 1/5 + ... + 1/(53) - 1/(55))`
`1/2B = (1 - 1/(55))`
`1/2B = (54)/(55)`
`B =(54)/(55) : 1/2`
`B = (54)/(55) * 2`
`B =(108)/(55)`
tính
\(B=\dfrac{1}{1.3}+\dfrac{1}{3.5}+\dfrac{1}{5.7}+...+\dfrac{1}{97.99}\)
Tính
\(\dfrac{1}{1.3}\)+ \(\dfrac{1}{3.5}\)+\(\dfrac{1}{5.7}\)+...+\(\dfrac{1}{2021.2023}\)
Tính nhanh:
\(A=\dfrac{1}{1.3}+\dfrac{1}{3.5}+\dfrac{1}{5.7}+...+\dfrac{1}{2021.2023}\)
tính tổng các phân số sau:
a)\(\dfrac{1}{1.2}\)+\(\dfrac{1}{2.3}\)+\(\dfrac{1}{3.4}\)+❓+\(\dfrac{1}{2003.2004}\)
b)\(\dfrac{1}{1.3}\)+\(\dfrac{1}{3.5}\)+\(\dfrac{1}{5.7}\)+❓\(\dfrac{1}{2003.2005}\)
tính tổng có quy luật :
H=\(\dfrac{1}{1.3}\)+\(\dfrac{1}{3.5}\)+\(\dfrac{1}{5.7}\)+......+\(\dfrac{1}{47.49}\)+\(\dfrac{1}{49.51}\)
\(\dfrac{1}{1.3}\) +\(\dfrac{1}{3.5}\) +\(\dfrac{1}{5.7}\) +.....+\(\dfrac{1}{2003.2005}\)
bài 4 : tính
A = \(\dfrac{1}{1.3}\) + \(\dfrac{1}{3.5}\) + \(\dfrac{1}{5.7}\) + ...+ \(\dfrac{1}{2021.2023}\)
mọi người giải giúp em bài này nha
Tính hợp lí:
A=\(\dfrac{3}{1.3}+\dfrac{3}{3.5}+\dfrac{3}{5.7}+...+\dfrac{3}{49.51}\)
B=\(\dfrac{1}{3}+\dfrac{1}{3^2}+\dfrac{1}{3^3}+...+\dfrac{1}{3^8}\)
Giúp mik nha mik đang cần rất là gấp nha !!!!!!!!!!
\(\dfrac{1}{1.3}\) + \(\dfrac{1}{3.5}\) + \(\dfrac{1}{5.7}\) +......+ \(\dfrac{1}{(2x-1)(2x+1)}\) = \(\dfrac{49}{99}\)
HeLp me
tiếp help A=\(\dfrac{1}{1.3}\)+\(\dfrac{1}{3.5}\)+\(\dfrac{1}{5.7}\)+.....+\(\dfrac{1}{99.101}\) help me :)
