Tính Nhanh:
\(B=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{9900}\)\
Giúp mk nha, cần gấp. Ai nhanh đúng tik cho
\(C=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}\)
Ai nhanh và đúng nhất mk sẽ tik!!!
\(C=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}\)
\(C=1\times\frac{1}{2}+\frac{1}{2}\times\frac{1}{3}+\frac{1}{3}\times\frac{1}{4}+\frac{1}{4}\times\frac{1}{5}+\frac{1}{5}\times\frac{1}{6}\)
\(C=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}\)
\(C=1-\frac{1}{6}\)
\(C=\frac{5}{6}\)
\(C=\frac{30}{60}+\frac{10}{60}+\frac{5}{60}+\frac{3}{60}+\)\(\frac{2}{60}\)
\(C=\frac{30+10+5+3+2}{60}\)
\(C=\frac{50}{60}=\frac{5}{6}\)
\(A=\frac{\frac{1}{39}-\frac{1}{6}-\frac{1}{51}}{\frac{1}{8}-\frac{1}{52}+\frac{1}{68}}:5\frac{1}{6}\)
tính hợp lí nha
bạn nào trl nhanh và đúng nhật mk sẽ tik(mk cần gấp)
\(2+\frac{2}{3}+\frac{2}{12}+.....+\frac{2}{X\left(X-1\right)}=1\frac{1989}{1991}\)
1989 PHẦN 1991 NHA MK VT THIẾU
\(\frac{1}{21}+\frac{1}{28}+\frac{1}{36}+.....+\frac{2}{X\left(X+1\right)}=\frac{2}{9}\) \(X-\frac{20}{11.13}-\frac{20}{13.15}-\frac{20}{15.17}-.....-\frac{20}{53.55}=\frac{3}{11}\)
GIÚP MÌNH NHA MẤY BẠN 10H CHỐT NHA . AI TRẢ LỜI ĐÚNG VÀ NHANH MK TIK CHO
Cho A = \(\frac{9}{1}+\frac{8}{2}+\frac{7}{3}+...+\frac{1}{9}\)
B = \(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{10}\)
Tính A : B.
Mik đang cần gấp ai làm nhanh và đúng nhất mik tik cho 3 cái lun nha!
từ đề bài ta có \(\frac{A}{B}=\frac{\frac{9}{1}+\frac{8}{2}+\frac{7}{3}+...+\frac{1}{9}}{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{10}}\)
\(\frac{A}{B}=\frac{\left(\frac{8}{2}+1\right)+\left(\frac{7}{3}+1\right)+...+\left(\frac{1}{9}+1\right)+1}{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{10}}\)
\(\frac{A}{B}=\frac{\frac{10}{2}+\frac{10}{3}+...+\frac{10}{9}+\frac{10}{10}}{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{10}}\)
\(\frac{A}{B}=\frac{10\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{10}\right)}{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{10}}\)
\(\frac{A}{B}=10\)
1 . tính nhanh
A = \(\frac{1}{2}\) + \(\frac{1}{6}\) + \(\frac{1}{12}\) + \(\frac{1}{20}\) + ............. \(\frac{1}{99.100}\)
mk cần gấp giúp mk sẽ like cho mỗi ngày nếu đúng
đơn giản :
A=\(\frac{1}{1.2}\)+\(\frac{1}{2.3}\)+\(\frac{1}{3.4}\)+........+\(\frac{1}{99.100}\)
A= \(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+.....+\frac{1}{99}-\frac{1}{100}\)
A=1 - \(\frac{1}{100}\)
A= \(\frac{99}{100}\)
CÓ AI DÙNG HỌC 24 GIỜ KO
A = 1/2 + 1/6 / + 1/ 12 + 1/20 + ......+ 1/(99.100)
A= 1/ ( 1 x 2 ) + 1/ ( 2 x 3 ) + 1 / ( 3 x 4 ) + .....+ 1/ ( 99 x 100 )
A = 1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 + .................+ 1/99 - 1/100
A= 1 - 1/100
A= 99/100
CHÚC BẠN HỌC TỐT
ta có:
\(A=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+....+\frac{1}{99\cdot100}\)
=>\(A=\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+....+\frac{1}{99\cdot100}\)
=>\(A=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+....+\frac{1}{99}-\frac{1}{100}\)
=>\(A=1-\frac{1}{100}\)
=>\(A=\frac{99}{100}\)
vậy \(A=\frac{99}{100}\)
tính
1/\(\frac{\left(\frac{3}{10}-\frac{4}{15}-\frac{7}{20}\right).\frac{5}{9}}{\left(\frac{1}{4}+\frac{1}{7}-\frac{-3}{35}\right).\left(-1\frac{1}{3}\right)}\)
2/\(\frac{0,6-\frac{1}{3}+\frac{3}{11}}{1,4-\frac{7}{9}+\frac{7}{11}}-\frac{\frac{1}{3}-0,25+\frac{1}{5}}{1\frac{1}{6}-0,875+0,7}\)
các bn lm giúp mk vs!!!!
mk đang cần gấp lắm nha!!!!!!!!!
ai lm nhanh nhất đúng đủ trình bày khoa học mk tick cho !!!!!!!1
\(D=\left(1-\frac{1}{2}\right)+\left(1-\frac{1}{6}\right)+\left(1-\frac{1}{12}\right)+\left(1-\frac{1}{20}\right)\)
Nhanh nha Mk cần gấp lắm rồi
\(D=\left(1-\frac{1}{2}\right)+\left(1-\frac{1}{6}\right)+\left(1-\frac{1}{12}\right)+\left(1-\frac{1}{20}\right)\)
\(=\left(1+1+1+1\right)-\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}\right)\)
\(=4-\left(\frac{2-1}{1.2}+\frac{3-2}{2.3}+\frac{4-3}{3.4}+\frac{5-4}{4.5}\right)\)
\(=4-\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}\right)\)
\(=4-\left(1-\frac{1}{5}\right)=4-\frac{4}{5}=\frac{16}{5}\)
\(D=1-\frac{1}{2}+1-\frac{1}{6}+1-\frac{1}{12}+1-\frac{1}{20}\)
\(D=\left(1+1+1+1\right)-\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}\right)\)
\(D=4-\frac{4}{5}\)
\(D=\frac{16}{5}\)
D=\(\frac{1}{2}+\frac{5}{6}+\frac{11}{12}+\frac{19}{20}\)= \(\left(\frac{1}{2}+\frac{19}{20}\right)+\left(\frac{5}{6}+\frac{11}{12}\right)\)=\(\left(\frac{10}{20}+\frac{19}{20}\right)+\left(\frac{10}{12}+\frac{11}{12}\right)\)
= \(\frac{29}{20}+\frac{7}{4}\)=\(\frac{29}{20}+\frac{35}{20}=\frac{64}{20}=\frac{16}{5}\)
\(\frac{1}{3}+\frac{5}{6}:\left(X-2\frac{1}{5}\right)=\frac{3}{4}\)
Các bn giúp mk phép tìm X này nha!Ai nhanh mk cho 3 tik
\(\frac{1}{3}\) + \(\frac{5}{6}\): \(\left(x-2\frac{1}{5}\right)\)= \(\frac{3}{4}\)
<=> \(\frac{5}{6}\):\(\left(x-2\frac{1}{5}\right)\)= \(\frac{3}{4}\)- \(\frac{1}{3}\)
<=> \(\frac{5}{6}\) : \(\left(x-2\frac{1}{5}\right)\) = \(\frac{5}{12}\)
<=> \(\left(x-2\frac{1}{5}\right)\) = \(\frac{5}{6}\) : \(\frac{5}{12}\)
,<=> \(\left(x-2\frac{1}{5}\right)\)= 2
<=. x = 2 + \(\frac{11}{5}\)
<=> x = \(\frac{21}{5}\)
1) tính tổng nghen
a)\(\frac{1}{2}\)+\(\frac{1}{6}\)+\(\frac{1}{12}\)+\(\frac{1}{20}\)+\(\frac{1}{30}\)+.....+\(\frac{1}{9900}\)
b)1+2+2^2+2^3+....+2^2018
tính giúp mk với nhé,đúng tick cho
Bài 1:
a) \(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+...+\frac{1}{9900}\)
\(=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+...+\frac{1}{99.100}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+...+\frac{1}{99}-\frac{1}{100}\)
\(=1-\frac{1}{100}\)
\(=\frac{99}{100}\)
b) ta có: \(A=1+2+2^2+2^3+...+2^{2018}\)
\(\Rightarrow2A=2+2^2+2^3+2^4+...+2^{2019}\)
\(\Rightarrow2A-A=2^{2019}-2\)
\(\Rightarrow A=2^{2019}-2\)
Chúc bn học tốt !!!!!
a, \(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{9900}\)
\(=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{99.100}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{99}-\frac{1}{100}\)
\(=1-\frac{1}{100}=\frac{99}{100}\)