\(\frac{2}{11\cdot13}+\frac{2}{13\cdot15}+...+\frac{2}{19\cdot21}-x+4+\frac{221}{231}=\frac{7}{3}\)
ai nhanh tick ( giải đầy đủ nha )
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Những câu hỏi liên quan
2 tháng 3 2016
(2/143+2/195+2/255+2/323+2/399).462-y=19
=> 10/231.462-y=19
=> 20-y=19
=> y= 20-19=1
DUYỆT NHA "T I C K"
5 tháng 8 2017
\(\left(\frac{2}{11.13}+\frac{2}{13.15}+.........+\frac{2}{19.21}\right)x623-24,808:\left(y+0,5\right)+12,04=30\)
Ta tính bên trong ngoặc:
\(\frac{2}{11.13}+\frac{2}{13.15}+..........+\frac{2}{19.21}\)
= \(\frac{2}{11}-\frac{2}{13}+\frac{2}{13}-\frac{2}{15}+...........+\frac{2}{19}-\frac{2}{21}\)
= \(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+.........+\frac{1}{19}-\frac{1}{21}\)
=> \(\frac{1}{11}-\frac{1}{19}\)= \(\frac{8}{209}\)
=> \(\frac{8}{209}x623-24,808:\left(y+0,5\right)+12,04=30\)
Tiếp tục làm tiếp nhé
5 tháng 8 2017
Nhầm mk làm lại:
\(\frac{1}{11}-\frac{1}{21}=\frac{10}{231}\)
=> \(\frac{10}{231}x623-24,808:\left(y+05\right)+12,04=30\)
\(\frac{890}{33}\)- 24,808 : .......
Làm tiếp đi nhé
5 tháng 2 2022
Bài 1:
\(\Leftrightarrow\left(\dfrac{1}{11}-\dfrac{1}{21}\right)\cdot462-\left[2.04:\left(x+1.05\right)\right]:0.12=19\)
\(\Leftrightarrow\left[2.04:\left(x+1.05\right)\right]:0.12=1\)
\(\Leftrightarrow2.04:\left(x+1.05\right)=0.12\)
\(\Leftrightarrow x+1.05=17\)
hay x=15,85
6 tháng 4 2017
giai câu a
a) ta có (\(\frac{2}{11.13}\)+\(\frac{2}{13.15}\)+.....+\(\frac{2}{19.21}\))*462 - x =19
(\(\frac{1}{11}\)-\(\frac{1}{13}\)+\(\frac{1}{13}\)-\(\frac{1}{15}\)+....+\(\frac{1}{19}\)-\(\frac{1}{21}\)) * 462 -x=19
(\(\frac{1}{11}\)-\(\frac{1}{21}\))*462-x=19
TA
26 tháng 9 2020
\(\frac{33}{2}+\frac{33}{6}+\frac{33}{18}+\frac{33}{54}+\frac{33}{162}+\frac{33}{486}\)
\(=\frac{33.3+33.3+33.3+33.3+33.3}{486}\)
\(=\frac{99.5}{486}\)
\(=\frac{495}{486}\)
26 tháng 9 2020
Gọi \(A=\frac{33}{2}+\frac{33}{6}+...+\frac{33}{486}\)
\(A=33.\left[\left(\frac{1}{1.2}+\frac{1}{2.3}\right)+\left(\frac{1}{3.6}+\frac{1}{6.9}\right)\left(\frac{1}{9.18}+\frac{1}{18.27}\right)\right]\)
\(A=33.\left[\frac{2}{3}+\frac{2}{9}+\frac{2}{27}\right]\)
\(A=66.\left[\frac{9}{27}+\frac{3}{27}+\frac{1}{27}\right]\)
\(A=66.\frac{13}{27}\)
\(A=\frac{286}{9}\)
sai hay đúng cx ko biết nha
=> 1/11 - 1/13 + 1/13 - 1/15 + ..... + 1/19 - 1/21 - x + 4 + 221/231 = 7/3
=> 1/11 - 1/21 - x + 4 + 221/231 = 7/3
=> 2099/420 - x = 7/3
=> x = 2099/420 - 7/3 = 373/140
Tk mk nha
Bài làm
\(\frac{2}{11.13}+\frac{2}{13.15}+...+\frac{2}{19.21}-x+4+\frac{221}{231}=\frac{7}{3}\)
\(\Leftrightarrow2\left(\frac{1}{11.13}+\frac{1}{13.15}+...+\frac{1}{19.21}\right)-x+4+\frac{221}{231}=\frac{7}{3}\)
\(\Leftrightarrow2\left(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+...+\frac{1}{19}-\frac{1}{21}\right)-x+4+\frac{221}{231}=\frac{7}{3}\)
\(\Leftrightarrow2\left(\frac{1}{11}-\frac{1}{21}\right)-x+4+\frac{221}{231}=\frac{7}{3}\)
\(\Leftrightarrow2.\frac{10}{231}-x+4+\frac{221}{231}=\frac{7}{3}\)
\(\Leftrightarrow\frac{20}{231}-x+4+\frac{221}{231}=\frac{7}{3}\)
\(\Leftrightarrow\frac{20}{231}-x+\frac{924}{231}+\frac{221}{231}=\frac{539}{231}\)
\(\Leftrightarrow\frac{20}{231}-x+\frac{924}{231}=\frac{539}{231}-\frac{221}{231}\)
\(\Leftrightarrow\frac{20}{231}-x+\frac{924}{231}=\frac{318}{231}\)
\(\Leftrightarrow\frac{20}{231}-x=\frac{318}{231}-\frac{924}{231}\)
\(\Leftrightarrow\frac{20}{231}-x=-\frac{606}{231}\)
\(\Leftrightarrow x=\frac{20}{231}-\frac{606}{231}\)
\(\Leftrightarrow x=-\frac{586}{231}\)
Vậy \(\Leftrightarrow=-\frac{586}{231}\)