CMR:
A) \(\frac{113}{342}>\frac{251}{755}\) VÀ
B)\(\frac{1784}{3456}>\frac{673}{1234}\) là ko đúng
Câu này cho các bạn CTV:
Tính giá trị biểu thức: \(\frac{-1123}{123}+123-\frac{1234}{3456}\)
CTV đâu vào trả lời đi
Cơ hội trả lời đó
Dành riêng luôn
\(-\frac{1123}{123}+123-\frac{1234}{3456}\)
\(=\frac{14006}{123}-\frac{1234}{3456}\)
\(=113,5128585\)
ko quy đồng hãy so sánh \(A=\frac{-5}{10^{2009}}+\frac{-17}{10^{2010}}vàB=\frac{-17}{10^{2009}}+\frac{-5}{10^{2010}}\)
cu lay phep tinh nay tru phep tinh kia hk ra thi nt hoi mink
1) có thể tìm đc 2 số nguyên x,y sao cho 45x+10y=-20152016 ko?
2)CMR:A=\(\frac{1}{41}+\frac{1}{42}+\frac{1}{43}+\frac{1}{44}+\frac{1}{45}+...+\frac{1}{80}>\frac{7}{12}\)
gọi 1/41+1/42+1/43+...+1/79+1/80 là A
ta có:1/41>1/60,1/42>1/60,1/43>1/60,...,1/60=1/60
=>1/41+1/42+1/43+...+1/60>1/60
1/61>1/80,..................................,1/80=1/80
=>1/61+1/62+............+1/80>1/80
=>1/41+1/42+1/43+...+1/79+1/80>1/60+1/80
lại có 7/12=1/4+1/3
1/60.20=1/3 và 1/80.20=1/4
=>1/41+1/42+1/43+...+1/79+1/80>1/3+1/4
=>1/41+1/42+1/43+...+1/79+1/80>7/12
Tính tổng :
\(\frac{1}{7}+\frac{1}{91}+\frac{1}{247}+\frac{1}{475}+\frac{1}{755}+\frac{1}{1147}\)
\(\frac{1}{7}+\frac{1}{91}+\frac{1}{247}+\frac{1}{475}+\frac{1}{755}+\frac{1}{1147}\)
\(=\frac{1}{7}+\frac{1}{7.13}+\frac{1}{13.19}+\frac{1}{19.25}+\frac{1}{25.31}+\frac{1}{31.37}\)
\(=\frac{1}{6}\left(1-\frac{1}{37}\right)\)
\(=\frac{1}{6}.\frac{36}{37}\)
\(=\frac{6}{37}\)
\(\frac{1}{7}+\frac{1}{91}+\frac{1}{247}+\frac{1}{475}+\frac{1}{755}+\frac{1}{1147}\)
\(=\frac{1}{1.7}+\frac{1}{7.13}+\frac{1}{13.19}+\frac{1}{19.25}+\frac{1}{25.31}+\frac{1}{31.37}\)
\(=\frac{1}{6}.\left(\frac{6}{1.7}+\frac{6}{7.13}+\frac{6}{13.19}+\frac{6}{19.25}+\frac{6}{25.31}+\frac{6}{35.37}\right)\)
\(=\frac{1}{6}.\left(1-\frac{1}{7}+\frac{1}{7}-\frac{1}{13}+\frac{1}{13}-\frac{1}{19}+\frac{1}{19}-\frac{1}{25}+\frac{1}{25}-\frac{1}{31}+\frac{1}{31}-\frac{1}{37}\right)\)
\(=\frac{1}{6}.\left(1-\frac{1}{37}\right)\)
\(=\frac{1}{6}.\frac{36}{37}=\frac{6}{37}\)
~ Hok tốt ~
\(\frac{1}{6}\left(\frac{6}{7}+\frac{6}{91}+\frac{6}{247}+\frac{6}{475}+\frac{6}{755}+\frac{6}{1147}\right)\)
\(=\frac{1}{6}\left(\frac{6}{1\cdot7}+\frac{6}{7\cdot13}+\frac{6}{13\cdot19}+\frac{6}{19\cdot25}+\frac{6}{25\cdot31}+\frac{6}{31\cdot37}\right)\)
\(=\frac{1}{6}\left(1-\frac{1}{7}+\frac{1}{7}-\frac{1}{13}+\frac{1}{13}-\frac{1}{19}+\frac{1}{19}-\frac{1}{25}+\frac{1}{25}-\frac{1}{31}+\frac{1}{31}-\frac{1}{37}\right)\)
\(=\frac{1}{6}\left(1-\frac{1}{37}\right)\)
\(\frac{1}{6}\left(\frac{37}{37}-\frac{1}{37}\right)=\frac{1}{6}\cdot\frac{36}{37}=\frac{1\cdot6\cdot6}{6\cdot37}=\frac{6}{37}\)
So sánh :
\(a.A=\frac{20^{10}+1}{20^{10}-1}vàB=\frac{20^{10}-1}{20^{10}-3}\)
\(b.A=\frac{10^{15}+1}{10^{16}+1}vàB=\frac{10^{16}+1}{10^{17}+1}\)
\(c.A=\frac{2013^5+2000}{2013^6+2000}vàB=\frac{2013^{10}+2000}{2013^{11}+2000}\)
Minh chi biet lam cau b thoi ak
b) Giai:
B=10^16+1 tren 10^17 +1 <10^16+1+9 tren 10^17+1+9
ma 10^16+1+9 tren 10^17+1+9 = 10^16+10 tren 10^17+10
=10(10^15+1) tren 10(10^16+1)
=10^15+1 tren 10^16+1 =A
=>A>B
Cho y kien voi!
DÀI LẮM BN AK MK KO VIẾT NỔI
mik cam on pn nhiu ,sau nay dug ai cmt lug tug nha....
cho A=\(\frac{1}{1.2}+\frac{1}{3.4}+\frac{1}{5.6}+...+\frac{1}{99.100}vàB=\frac{2013}{51}+\frac{2013}{52}+\frac{2013}{53}+...+\frac{2013}{100}\)
Chứng Minh \(\frac{B}{A}\)là số nguyên
http://olm.vn/hoi-dap/question/126681.html
Bạn tham khảo nhé
Cho A=\(\frac{79}{1999}+\frac{191}{1998}+\frac{947}{1997}+\frac{673}{1998}+\frac{110}{1999}\)
\(A=\frac{79}{1999}+\frac{191}{1998}+\frac{947}{1997}+\frac{673}{1998}+\frac{110}{1999}\)
\(A=\left(\frac{79}{1999}+\frac{110}{1999}\right)+\left(\frac{191}{1998}+\frac{673}{1998}\right)+\frac{947}{1997}\)
\(A=\frac{189}{1999}+\frac{16}{37}+\frac{947}{1997}\)
SO SÁNH : A=\(\frac{10^{20}+10}{10^{19}+10}vàB=\frac{10^{19}+10}{10^{18}+10}\)ai làm đúng mk tick cho nhanh nha mk đàng cần gấp
cho A=40+\(\frac{8}{3}+\frac{7}{8^2}\frac{5}{8^3}\frac{32}{8^5}vàB=\frac{24}{8^2}+40+\frac{5}{8^2}+\frac{40}{8^2}\frac{5}{8^4}.\)