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![](https://rs.olm.vn/images/avt/0.png?1311)
999999999,9999999999km2 k cho minh nha
đảm bảo đúng 10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000% lun
9999999999999999999999999999999999999999999999999999999999999999999999999999999 nha đúng 1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000%
![](https://rs.olm.vn/images/avt/0.png?1311)
Mình xin lỗi các bạn mình không đăng được hình lên có bạn nào chỉ giúp mình đăng hình !!! Mình cảm ơn !!!
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Tớ không chắc thế này có phải tính nhanh hay ko nữa 0w0?
Tớ thấy các tử số ở đây đều chia hết cho 32 nên:
\(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\)\(\frac{1}{32}\)
= \(\frac{16}{32}+\frac{8}{32}+\frac{4}{32}+\frac{2}{32}+\frac{1}{32}+\frac{1}{32}\)
= \(\frac{16+8+4+2+1+1}{32}\)
= \(\frac{32}{32}=1\)
#z
![](https://rs.olm.vn/images/avt/0.png?1311)
\(C1:\left(\frac{1}{3}+\frac{1}{5}\right)x\frac{1}{2}\)
\(=\left(\frac{5}{15}+\frac{3}{15}\right)x\frac{1}{2}\)
\(=\frac{8}{15}x\frac{1}{2}\)
\(=\frac{4}{15}\)
~ Học tốt ~
\(C2:(\frac{1}{3}+\frac{1}{5})x\frac{1}{2}\)
\(=\frac{1}{2}x\frac{1}{3}+\frac{1}{2}x\frac{1}{5}\)
\(=\frac{1}{6}+\frac{1}{10}\)
\(=\frac{3}{30}+\frac{5}{30}\)
\(=\frac{8}{30}=\frac{4}{15}\)
~ Học tốt ~
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{1}{2}+\frac{1}{2}+\frac{3}{4}+\frac{5}{10}+\frac{4}{6}+\frac{5}{20}\)
\(=\frac{1}{2}+\frac{1}{2}+\frac{3}{4}+\frac{1}{2}+\frac{2}{3}+\frac{1}{4}\)
\(=\left(\frac{1}{2}+\frac{1}{2}\right)+\left(\frac{3}{4}+\frac{1}{4}\right)+\left(\frac{1}{2}+\frac{2}{3}\right)\)
\(=1+1+\frac{7}{6}\)
\(=2+\frac{7}{6}=\frac{19}{6}.\)
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Ta có :
B = 1/3.5 + 1/5.7 + 1/7.9 + 1/9.11 + 1/11.13
2B = 2/3.5 + 2/5.7 + 2/7.9 + 2/9.11 +2/11.13
2B = 1/3 - 1/5 + 1/5 - 1/7 + 1/7 - 1/9 + 1/9 - 1/11 + 1/11 - 1/13
2B = 1/3 - 1/13
2B = 10/39
B = 10/39 : 2
B = 5/39
\(B=\frac{1}{15}+\frac{1}{35}+\frac{1}{63}+\frac{1}{99}+\frac{1}{143}\)
\(B=\frac{1}{3.5}+\frac{1}{5.7}+\frac{1}{7.9}+\frac{1}{9.11}+\frac{1}{11.13}\)
\(B=\frac{1}{2}\left(\frac{1}{3.5}+\frac{1}{5.7}+..+\frac{1}{11.13}\right)\)
\(B=\frac{1}{2}\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{11}-\frac{1}{13}\right)\)
\(B=\frac{1}{2}\left(\frac{1}{3}-\frac{1}{13}\right)\)
\(B=\frac{1}{2}\cdot\frac{10}{39}=\frac{5}{39}\)
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---- { (110 + 1) . [(110-1):1+1] } : 2 = 12210
----- { (2021+0) . [(2012-0):1+ 1 } :2 = 4086462
Công thức áp dụng :
Tổng : [(số cuối + số đầu) . số số hạng] : 2
Số số hạng : (số cuối - số đầu) : khoảng cách giữa các số + 1
![](https://rs.olm.vn/images/avt/0.png?1311)
bài 1,2 tự làm
bài 3
\(\frac{n}{n+1}=\frac{n.\left(n+2\right)}{\left(n+1\right).\left(n+2\right)}=\frac{n^2+2n}{n^2+2n+n+2}\)
\(\frac{n+1}{n+2}=\frac{\left(n+1\right).\left(n+1\right)}{\left(n+1\right).\left(n+2\right)}=\frac{n^2+2n+1}{n^2+2n+n+2}\)
\(n^2+2n< n^2+2n+1=>...\)
đến đây tự làm nha khuya rồi mk buofonf ngủ lắm