11 tháng 5 2023 lúc 19:57
Các câu hỏi tương tự
23 tháng 8 2023 lúc 20:35
Sdfrac{1}{2^2}+dfrac{1}{3^2}+dfrac{1}{4^2}+...+dfrac{1}{9^2}dfrac{1}{2.3}+dfrac{1}{3.4}+dfrac{1}{4.5}...+dfrac{1}{9.10} dfrac{1}{2^2}+dfrac{1}{3^2}+dfrac{1}{4^2}+...+dfrac{1}{9^2}dfrac{1}{2}-dfrac{1}{3}+dfrac{1}{3}-dfrac{1}{4}+dfrac{1}{4}-dfrac{1}{5}+...+dfrac{1}{9}-dfrac{1}{10} dfrac{1}{2^2}+dfrac{1}{3^2}+dfrac{1}{4^2}+...+dfrac{1}{9^2}dfrac{1}{2}-dfrac{1}{10} dfrac{1}{2^2}+dfrac{1}{3^2}+dfrac{1}{4^2}+...+dfrac{1}{9^2}dfrac{2}{5}Sdfrac{1}{2^2}+dfrac{1}{3^2}+dfrac{1}{4^2}+...+dfrac{1}{9^2} df...
Đọc tiếp
S=\(\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+...+\dfrac{1}{9^2}>\dfrac{1}{2.3}+\dfrac{1}{3.4}+\dfrac{1}{4.5}...+\dfrac{1}{9.10}\)
=\(\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+...+\dfrac{1}{9^2}>\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+...+\dfrac{1}{9}-\dfrac{1}{10}\)
=\(\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+...+\dfrac{1}{9^2}>\dfrac{1}{2}-\dfrac{1}{10}\)
=\(\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+...+\dfrac{1}{9^2}>\dfrac{2}{5}\)
S=\(\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+...+\dfrac{1}{9^2}< \dfrac{1}{1.2}+\dfrac{1}{2.3}+\dfrac{1}{3.4}+...+\dfrac{1}{8.9}\)
=\(\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+...+\dfrac{1}{9^2}< 1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{8}-\dfrac{1}{9}\)
=\(\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+...+\dfrac{1}{9}< 1-\dfrac{1}{9}\)
=\(\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+...+\dfrac{1}{9^2}< \dfrac{8}{9}\)
Vậy \(\dfrac{2}{5}< S< \dfrac{8}{9}\)
Rút gọn các biểu thức sau:
a) A 1 + dfrac{1}{3} + dfrac{1}{3^2} + dfrac{1}{3^3} +...+ dfrac{1}{3^n}
b) B dfrac{1}{2} - dfrac{1}{2^2} + dfrac{1}{2^3} - dfrac{1}{2^4} +...+ dfrac{1}{2^{99}} - dfrac{1}{2^{100}}
c) C dfrac{3}{2^2} x dfrac{8}{3^2} x dfrac{15}{4^2} ... dfrac{899}{30^2}
(Mình cần gấp ạ)
Đọc tiếp
Rút gọn các biểu thức sau:
a) A = 1 + \(\dfrac{1}{3}\) + \(\dfrac{1}{3^2}\) + \(\dfrac{1}{3^3}\) +...+ \(\dfrac{1}{3^n}\)
b) B = \(\dfrac{1}{2}\) - \(\dfrac{1}{2^2}\) + \(\dfrac{1}{2^3}\) - \(\dfrac{1}{2^4}\) +...+ \(\dfrac{1}{2^{99}}\) - \(\dfrac{1}{2^{100}}\)
c) C = \(\dfrac{3}{2^2}\) x \(\dfrac{8}{3^2}\) x \(\dfrac{15}{4^2}\) ... \(\dfrac{899}{30^2}\)
(Mình cần gấp ạ)
1 tháng 10 2023 lúc 14:29
a) 0,25-dfrac{2}{3}+1dfrac{1}{4}b) dfrac{3^2}{2}:dfrac{1}{4}+dfrac{3}{4}.2010c) {[(dfrac{1}{25}-0,6)2:dfrac{49}{125}].dfrac{5}{6}}-[(dfrac{-1}{3})+dfrac{1}{2}]d) (-dfrac{1}{2}-dfrac{1^{ }}{3})2:[(dfrac{-5}{36})-(dfrac{-5}{36})0]Mn giúp mk nhé mk gấp quá tí đi học ai làm được mk thả tim và like nhé
Đọc tiếp
a) 0,25-\(\dfrac{2}{3}\)+1\(\dfrac{1}{4}\)
b) \(\dfrac{3^2}{2}\):\(\dfrac{1}{4}\)+\(\dfrac{3}{4}\).2010
c) {[(\(\dfrac{1}{25}\)-0,6)2:\(\dfrac{49}{125}\)].\(\dfrac{5}{6}\)}-[(\(\dfrac{-1}{3}\))+\(\dfrac{1}{2}\)]
d) (-\(\dfrac{1}{2}\)-\(\dfrac{1^{ }}{3}\))2:[(\(\dfrac{-5}{36}\))-(\(\dfrac{-5}{36}\))0]
Mn giúp mk nhé mk gấp quá tí đi học ai làm được mk thả tim và like nhé
\(\dfrac{x-1}{21}=\dfrac{3}{x+1}\)
\(2\dfrac{1}{2}x+x=2\dfrac{1}{17}\)
\(\left(x+\dfrac{1}{4}-\dfrac{2}{3}\right):\left(2+\dfrac{1}{6}-\dfrac{1}{4}\right)=\dfrac{7}{46}\)
\(2\dfrac{1}{3}x-1\dfrac{3}{4}x+2\dfrac{2}{3}=3\dfrac{3}{5}\)
Giúp mình với ! Mình cần gấp
Bài 1.(2,5 điểm)Tìm x, biết:a) left(2dfrac{1}{3}+3dfrac{1}{2}right).x-4dfrac{1}{6}+3dfrac{1}{2}b) left(1dfrac{1}{3}+3dfrac{1}{2}right).x4dfrac{1}{6}-3dfrac{1}{2}c) dfrac{1}{3}-dfrac{7}{8}.xdfrac{1}{4}d) dfrac{3}{2}.x+dfrac{1}{7}dfrac{7}{8}.dfrac{64}{49}e) 5dfrac{1}{2}-left(dfrac{1}{4}.x+dfrac{2}{5}right)25%
Đọc tiếp
Bài 1.(2,5 điểm)Tìm x, biết:
a) \(\left(2\dfrac{1}{3}+3\dfrac{1}{2}\right).x=-4\dfrac{1}{6}+3\dfrac{1}{2}\)
b) \(\left(1\dfrac{1}{3}+3\dfrac{1}{2}\right).x=4\dfrac{1}{6}-3\dfrac{1}{2}\)
c) \(\dfrac{1}{3}-\dfrac{7}{8}.x=\dfrac{1}{4}\)
d) \(\dfrac{3}{2}.x+\dfrac{1}{7}=\dfrac{7}{8}.\dfrac{64}{49}\)
e) \(5\dfrac{1}{2}-\left(\dfrac{1}{4}.x+\dfrac{2}{5}\right)=25\%\)
18 tháng 3 2023 lúc 19:38
chứng minh rằng
a , \(\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{8}-\dfrac{1}{16}+...+\dfrac{1}{512}-\dfrac{1}{1024}\) < \(\dfrac{1}{3}\)
b , \(\dfrac{1}{3}-\dfrac{2}{3^2}+\dfrac{3}{3^3}-\dfrac{4}{3^4}+...+\dfrac{99}{3^{99}}-\dfrac{100}{3^{100}}\) < \(\dfrac{3}{16}\)
29 tháng 1 2022 lúc 11:20
Tìm x biết:a,3dfrac{1}{2}-dfrac{1}{2}xdfrac{2}{3}b,dfrac{1}{3}+dfrac{2}{3}:x-7c,dfrac{1}{3}x+dfrac{2}{5}left(x-1right)0d,left(2x-3right)left(6-2xright)0e,x:dfrac{3}{4}+dfrac{1}{4}-dfrac{2}{3}f,dfrac{-2}{3}-dfrac{1}{3}left(2x-5right)dfrac{3}{2}g,2left|dfrac{1}{2}x-dfrac{1}{3}right|-dfrac{3}{2}dfrac{1}{4}h,dfrac{3}{4}-2.left|2x-dfrac{2}{3}right|2i,left(-0,6x-dfrac{1}{2}right).dfrac{3}{4}-left(-1right)dfrac{1}{3}j,left(3x-1right)left(-dfrac{1}{2}x+5right)0k,dfrac{1}{4}+dfrac{1}{3}:left(2x-1right)-5...
Đọc tiếp
Tìm x biết:
\(a,3\dfrac{1}{2}-\dfrac{1}{2}x=\dfrac{2}{3}\)
\(b,\dfrac{1}{3}+\dfrac{2}{3}:x=-7\)
\(c,\dfrac{1}{3}x+\dfrac{2}{5}\left(x-1\right)=0\)
\(d,\left(2x-3\right)\left(6-2x\right)=0\)
\(e,x:\dfrac{3}{4}+\dfrac{1}{4}=-\dfrac{2}{3}\)
\(f,\dfrac{-2}{3}-\dfrac{1}{3}\left(2x-5\right)=\dfrac{3}{2}\)
\(g,2\left|\dfrac{1}{2}x-\dfrac{1}{3}\right|-\dfrac{3}{2}=\dfrac{1}{4}\)
\(h,\dfrac{3}{4}-2.\left|2x-\dfrac{2}{3}\right|=2\)
\(i,\left(-0,6x-\dfrac{1}{2}\right).\dfrac{3}{4}-\left(-1\right)=\dfrac{1}{3}\)
\(j,\left(3x-1\right)\left(-\dfrac{1}{2}x+5\right)=0\)
\(k,\dfrac{1}{4}+\dfrac{1}{3}:\left(2x-1\right)=-5\)
\(l,\left(2x+\dfrac{3}{5}\right)^2-\dfrac{9}{25}=0\)
\(m,3\left(3x-\dfrac{1}{2}\right)^3+\dfrac{1}{9}=0\)
\(n,60\%x+\dfrac{2}{3}x=\dfrac{1}{3}.6\dfrac{1}{3}\)
\(p,-5\left(x+\dfrac{1}{5}\right)-\dfrac{1}{2}\left(x-\dfrac{2}{3}\right)=\dfrac{3}{2}x-\dfrac{5}{6}\)
\(q,3\left(x-\dfrac{1}{2}\right)-5\left(x+\dfrac{3}{5}\right)=-x+\dfrac{1}{5}\)
1. Cho Ndfrac{1}{31}+dfrac{1}{32}+...+dfrac{1}{60}CMR dfrac{3}{5} N dfrac{4}{5}2. Cho Mdfrac{1}{3}-dfrac{2}{3^2}+dfrac{3}{3^3}-dfrac{4}{3^4}+...+dfrac{29}{3^{29}}-dfrac{30}{3^{30}}CMR M dfrac{3}{16}3. Cho Qdfrac{2}{3}+dfrac{8}{9}+dfrac{26}{27}+...+dfrac{3^{2021}-1}{3^{2021}}CMR Qdfrac{4041}{2}
Đọc tiếp
1. Cho N=\(\dfrac{1}{31}+\dfrac{1}{32}+...+\dfrac{1}{60}\)
CMR \(\dfrac{3}{5}< N< \dfrac{4}{5}\)
2. Cho M=\(\dfrac{1}{3}-\dfrac{2}{3^2}+\dfrac{3}{3^3}-\dfrac{4}{3^4}+...+\dfrac{29}{3^{29}}-\dfrac{30}{3^{30}}\)
CMR \(M< \dfrac{3}{16}\)
3. Cho Q=\(\dfrac{2}{3}+\dfrac{8}{9}+\dfrac{26}{27}+...+\dfrac{3^{2021}-1}{3^{2021}}\)
CMR \(Q>\dfrac{4041}{2}\)
12 tháng 3 2022 lúc 14:30
Tìm x biết:a,dfrac{4}{5}+xdfrac{2}{3}b,dfrac{-5}{6}-xdfrac{2}{3}c,dfrac{1}{2}x+dfrac{3}{4}dfrac{-3}{10}d,dfrac{x}{3}-dfrac{1}{2}dfrac{1}{5}e,dfrac{x+3}{15}dfrac{1}{3}h,x+30%x-1,3k,3dfrac{1}{3}x+16dfrac{1}{4}13,25m,dfrac{x-6}{2}dfrac{50}{x-6}n,x-13,424,5-6,7.5,2p,15,7x+3,6x-96,5q,2,5x-11,6-59,1
Đọc tiếp
Tìm x biết:
\(a,\dfrac{4}{5}+x=\dfrac{2}{3}\)
\(b,\dfrac{-5}{6}-x=\dfrac{2}{3}\)
\(c,\dfrac{1}{2}x+\dfrac{3}{4}=\dfrac{-3}{10}\)
\(d,\dfrac{x}{3}-\dfrac{1}{2}=\dfrac{1}{5}\)
\(e,\dfrac{x+3}{15}=\dfrac{1}{3}\)
\(h,x+30\%x=-1,3\)
\(k,3\dfrac{1}{3}x+16\dfrac{1}{4}=13,25\)
\(m,\dfrac{x-6}{2}=\dfrac{50}{x-6}\)
\(n,x-13,4=24,5-6,7.5,2\)
\(p,15,7x+3,6x=-96,5\)
\(q,2,5x-11,6=-59,1\)
-\(\dfrac{4}{7}\)+\(\dfrac{15}{4}\)-(\(\dfrac{11}{4}\)+\(\dfrac{3}{7}+\dfrac{1}{2}-\dfrac{1}{3}\))
\(\dfrac{1}{5}\left(\dfrac{1}{2}-\dfrac{1}{3}\right):\left(\dfrac{-9}{10}\right)+\dfrac{-7}{3}\)
\(\dfrac{-20}{23}+\dfrac{2}{3}-\dfrac{3}{23}+\dfrac{2}{5}+\dfrac{7}{15}\)
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