Các câu hỏi tương tự
Tính nhanh
\(\frac{2}{1\times3}+\frac{2}{3\times5}+\frac{2}{5\times7}+\frac{2}{7\times9}+\frac{2}{9\times11}\)
TÍNH NHANH:\(\frac{1}{1\times3\times5}+\frac{1}{2\times5\times8}+\frac{1}{3\times5\times7}+\frac{1}{5\times8\times11}+\frac{1}{5\times7\times9}+\frac{1}{8\times11\times14}+...+\frac{1}{995\times997\times999}+\frac{1}{1493\times1496\times1499}\)
\(\left(\frac{1}{1\times3}+\frac{1}{3\times5}+\frac{1}{5\times7}+\frac{1}{7\times9}+\frac{1}{9\times11}\right)\times y=\frac{2}{3}\)
Tìm y
Tính $Afrac{1}{5times7}+frac{1}{7times9}+frac{1}{9times11}+...+frac{1}{87times89}$A15×7+17×9+19×11+...+187×89.
Đáp số: A
Đọc tiếp
Tính $A=\frac{1}{5\times7}+\frac{1}{7\times9}+\frac{1}{9\times11}+...+\frac{1}{87\times89}$.
| Đáp số: A = | |
Bài 1 :
a, \(\frac{1}{2\times3}+\frac{1}{3\times4}+\frac{1}{4\times5}+...+\frac{1}{101\times102}\)
b, \(\frac{5}{5\times10}+\frac{5}{10\times15}+...+\frac{5}{115\times120}\)
c, \(\frac{2}{5\times7}+\frac{2}{7\times9}+\frac{2}{9\times11}+...+\frac{2}{997\times999}\)
Tìm x biết : \(x\times\left(\frac{2015}{8\times9}+\frac{1925}{9\times10}+\frac{1795}{10\times11}+\frac{1629}{11\times12}+6\right)=\frac{1}{24}\)
\(\frac{1}{1\times3}+\frac{1}{3\times5}+\frac{1}{5\times7}+........\frac{1}{2013\times2015}\)
tính tổng
A = 11 \(\frac{2}{1\times3}\)+11\(\frac{2}{3\times5}\)+ 11 \(\frac{2}{5\times7}\)+ 11\(\frac{2}{7\times9}\)+ 11\(\frac{2}{9\times11}\)
giúp mk với nhanh nhé
đề bài : Tính nhanh tổng A
tính:
a)
\(\frac{1}{10}+\frac{4}{20}+\frac{9}{30}+\frac{25}{50}+\frac{36}{60}+\frac{64}{80}+\frac{49}{70}+\frac{81}{90}\)
b)
\(\frac{2}{3\times5}+\frac{2}{5\times7}+\frac{2}{7\times9}+\frac{2}{9\times11}+...+\frac{2}{97\times99}\)
Ai làm nhanh mk cho 3 tik nha!