B = 3/2 + 3/6 + 3/12 + 3/15 +............... + 3/(n-1)n
C = 2/1.3 + 2/3.5 + 2/7.9 + ...................... + 2/30.32
D = 1/1.3 + 1/3.5 + ............. + 1/ ( n+1 )( n+3 )
Những câu hỏi liên quan
a) (frac{1}{2}+frac{1}{6}+frac{1}{12}+frac{1}{20}+...+frac{1}{132}) . x frac{1}{3}
b) (frac{2}{1.3}+frac{2}{3.5}+frac{2}{5.7}+frac{2}{7.9}+frac{2}{9.11}) : x frac{2}{3}
c) (frac{1}{1.3}+frac{1}{3.5}+frac{1}{5.7}+frac{1}{7.9}+frac{1}{9.11}) . x frac{2}{3}
Mik đang cần gấp
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a) (\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{132}\)) . x =\(\frac{1}{3}\)
b) (\(\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+\frac{2}{7.9}+\frac{2}{9.11}\)) : x = \(\frac{2}{3}\)
c) (\(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+\frac{1}{7.9}+\frac{1}{9.11}\)) . x = \(\frac{2}{3}\)
Mik đang cần gấp
a)(\(\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{11.12}\)). x=\(\frac{1}{3}\)
(1-\(\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-...-\frac{1}{11}_{ }+\frac{1}{12}\)).x=\(\frac{1}{3}\)
(1+\(\frac{1}{12}\)).x=\(\frac{1}{3}\)
x=\(\frac{1}{3}:\frac{13}{12}\)
x=\(\frac{4}{13}\)
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b)( \(2-\frac{2}{3}+\frac{2}{3}-\frac{2}{5}+...+\frac{2}{9}-\frac{2}{11}_{ }\)):x =\(\frac{2}{3}\)
Giống câu a
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Xem thêm câu trả lời
( 1/1.3+1/3.5+1/5.7+1/7.9+1/9.11). X = 2/3
\(\text{Ta có:}\) \(\left(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+\frac{1}{7.9}+\frac{1}{9.11}\right).x=\frac{2}{3}\)
\(\Leftrightarrow2.\left(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+\frac{1}{7.9}+\frac{1}{9.11}\right).x=\frac{2}{3}.2\)
\(\Leftrightarrow\left(\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+\frac{2}{7.9}+\frac{2}{9.11}\right).x=\frac{4}{3}\)
\(\Leftrightarrow\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+.....+\frac{1}{9}-\frac{1}{11}\right).x=\frac{4}{3}\)
\(\Leftrightarrow\left(1-\frac{1}{11}\right)x=\frac{4}{3}\)
\(\Leftrightarrow\frac{10}{11}x=\frac{4}{3}\)
\(\Leftrightarrow x=\frac{4}{3}:\frac{10}{11}=\frac{22}{15}\)
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Tính
A= 512 - 512/2 - 512/2^2 - 512/2^3 - ....- 512/210
E= 1 - 1/10 - 1/15 - 1/3 - 1/28 - 1/6 - 1/21
C= 11/1.3 + 47/3.5 + 107/5.7 + 191/7.9 +...+ 971/17.19
sai bet thang ngu nhu cho
Tìm y : ( 1/1.3 + 1/3.5 + 1/5.7 + 1/7.9 + 1/9.11 ) .y = 2/3.
( \(\frac{1}{1x3}\)+ \(\frac{1}{3x5}\)+....+\(\frac{1}{9x11}\)) x \(y\) = \(\frac{2}{3}\)
( \(\frac{2}{1x3}\)+ \(\frac{2}{3x5}\)+...+\(\frac{2}{9x11}\)) x \(y\) = \(\frac{4}{3}\) (nhân 2 vế lên với 2)
(1 - \(\frac{1}{3}\)+\(\frac{1}{3}\)-\(\frac{1}{5}\)+\(\frac{1}{5}\)- ...+ \(\frac{1}{9}\)- \(\frac{1}{11}\)) x \(y\)= \(\frac{4}{3}\)
( 1 - \(\frac{1}{11}\)) x \(y\)=\(\frac{4}{3}\)
\(\frac{10}{11}\) x \(y\) =\(\frac{4}{3}\)
\(y\) = \(\frac{4}{3}\): \(\frac{10}{11}\)
\(y\) = \(\frac{4}{3}\)x \(\frac{11}{10}\)
\(y\) =\(\frac{22}{15}\)
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kết quả đúng nhưng mình ko hiểu bạn có thể giáng lại ko ?
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Xem thêm câu trả lời
tìm y
[ 1/1.3+1/3.5+1/5.7+1/7.9 ] . y = 2/3
\(\left[\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+\frac{1}{7.9}\right].y=\frac{2}{3}\)
\(\Leftrightarrow\left[\frac{1}{1}-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}\right].y=\frac{2}{3}\)
\(\Leftrightarrow\left[\frac{1}{1}-\frac{1}{9}\right].y=\frac{2}{3}\)
\(\Leftrightarrow\frac{8}{9}.y=\frac{2}{3}\)
\(\Leftrightarrow y=\frac{2}{3}:\frac{8}{9}\)
\(\Leftrightarrow y=\frac{3}{4}\)
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a.Tính: 1/1-1/3; 1/3-1/5
b.Chứng minh rằng: 2/1.3= 1/1-1/3; 2/3.5=1/3-1/5
c.Tính: A=2/1.3+2/3.5+...+2/97.99+2/99.101
Giúp mk vs ạ mk sắp phải nộp r
a. \(\dfrac{1}{1}-\dfrac{1}{3}=\dfrac{3-1}{3}=\dfrac{2}{3}\); \(\dfrac{1}{3}-\dfrac{1}{5}=\dfrac{5-3}{15}=\dfrac{2}{15}\)
b. Ta có \(VP=\dfrac{1}{1}-\dfrac{1}{3}=\dfrac{2}{3}\) mà \(VP=\dfrac{2}{3}\) \(\Rightarrow VT=VP\)
Ta có \(VP=\dfrac{1}{3}-\dfrac{1}{5}=\dfrac{2}{15}\) mà \(VP=\dfrac{2}{3.5}=\dfrac{2}{15}\) \(\Rightarrow VT=VP\)
c. \(A=\dfrac{2}{1.3}+\dfrac{2}{3.5}+...+\dfrac{2}{97.99}+\dfrac{2}{99.101}\)
\(=2\left(\dfrac{1}{1.3}+\dfrac{1}{3.5}+...+\dfrac{1}{97.99}+\dfrac{1}{99.101}\right)\)
\(=2\left(1-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+...+\dfrac{1}{97}-\dfrac{1}{99}+\dfrac{1}{99}-\dfrac{1}{101}\right)\)
\(=2\left(1-\dfrac{1}{101}\right)\) \(=\dfrac{200}{101}\)
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a: \(\dfrac{1}{1}-\dfrac{1}{3}=1-\dfrac{1}{3}=\dfrac{2}{3}\)
\(\dfrac{1}{3}-\dfrac{1}{5}=\dfrac{2}{15}\)
b: \(\dfrac{1}{1}-\dfrac{1}{3}=\dfrac{3}{3}-\dfrac{1}{3}=\dfrac{2}{3}\)
\(\dfrac{1}{3}-\dfrac{1}{5}=\dfrac{5}{15}-\dfrac{3}{15}=\dfrac{2}{15}\)
c: Ta có: \(A=\dfrac{2}{1\cdot3}+\dfrac{2}{3\cdot5}+...+\dfrac{2}{97\cdot99}+\dfrac{2}{99\cdot101}\)
\(=1-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+...+\dfrac{1}{97}-\dfrac{1}{99}+\dfrac{1}{99}-\dfrac{1}{101}\)
\(=\dfrac{100}{101}\)
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Cho P =2 / 1.3+ 2/3.5 +...+ 2/ (2n+1).(2n+3). CMR P<1, n thuoc N*
\(P=\frac{1}{1}-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{2n+1}+\frac{1}{2n+3}\)
\(P=1-\frac{1}{2n+3}\)\(
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( Dấu chấm như . là nhân nhé ! )
A,
E = 1/3 + 1/6 + 1/10 + ........+ 1/55
B,
F = 2/1.3 + 2/3.5 + 2/5.7 +.........+ 3/13.15
C,
G = 3/1.3 + 3/3.5 + +3/5.7 + ..............+ 1/17.21
\(B=\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+..+\frac{1}{55}\)
\(B=\frac{2}{6}+\frac{2}{12}+\frac{2}{20}+...+\frac{2}{110}\)
\(B=\frac{2}{2.3}+\frac{2}{3.4}+\frac{2}{4.5}+...+\frac{2}{10.11}\)
\(B=2.\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{10}-\frac{1}{11}\right)\)
\(B=2.\left(\frac{1}{2}-\frac{1}{11}\right)=2.\frac{9}{22}=\frac{9}{11}\)
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bạn do not ask why làm sai ở bước 4 rồi
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tínhA frac{11}{1.3}+ frac{47}{3.5}+ frac{107}{5.7}+ frac{191}{7.9}+...+ frac{971}{17.19}B frac{2^{12}.3^5-2^{12}.3^4}{2^{12}.3^6+2^{12}.3^5}- frac{5^{10}.7^3-5^{10}.7^4}{5^9.7^3-5^9.7^3.2^3}C 1.3+3.5+5.7+...+ (2n-1)(2n+1)Giúp mình vs nhanh nhanh nha các bạn
Đọc tiếp
tính
A =\(\frac{11}{1.3}\)+ \(\frac{47}{3.5}\)+ \(\frac{107}{5.7}\)+ \(\frac{191}{7.9}\)+...+ \(\frac{971}{17.19}\)
B = \(\frac{2^{12}.3^5-2^{12}.3^4}{2^{12}.3^6+2^{12}.3^5}\)- \(\frac{5^{10}.7^3-5^{10}.7^4}{5^9.7^3-5^9.7^3.2^3}\)
C = 1.3+3.5+5.7+...+ (2n-1)(2n+1)
Giúp mình vs nhanh nhanh nha các bạn