( \(\frac{2}{11\cdot13}\)+ \(\frac{2}{13\cdot15}\)+.......+\(\frac{2}{19\cdot21}\)) x 623 - 24,808 :(y+0,5) +12,04=30
Những câu hỏi liên quan
(\(\frac{2}{11\cdot13}+\frac{2}{13\cdot15}+...+\frac{2}{19\cdot21}\)) * 462 - 2,04 : (x+1,5) + 11,02 = 30
\(\left(\frac{2}{11\cdot13}+\frac{2}{13\cdot15}+\frac{2}{15\cdot17}+\frac{2}{17\cdot19}+\frac{2}{19\cdot21}\right)\cdot462-y=19\)
(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"
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Tìm x biết : \(\left(\frac{2}{11\cdot13}+\frac{2}{13\cdot15}+....+\frac{2}{19\cdot21}\right)\cdot462-\left(2,04:\left(x+1,05\right)\right):0,12=19\)
\(\frac{2}{11\cdot13}+\frac{2}{13\cdot15}+...+\frac{2}{19\cdot21}-x+4+\frac{221}{231}=\frac{7}{3}\)
ai nhanh tick ( giải đầy đủ nha )
=> 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
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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 \(\Leftrightarrow=-\frac{586}{231}\)
ta có : 2/11*15 +2/13*15+...+2/19*21 - x +4+221/231=7/3
=>(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
<=>10/231 - x+4 +221/231 =7/3
<=>1-x +4=7/3
<=>x+4=1-7/3
<=>x+4=-4/3
<=>x=-4/3-4
<=>x=-16/3
vậy x=-16/3
\(\left(\frac{2}{11\cdot13}+\frac{2}{13\cdot15}+\frac{2}{15\cdot17}+\frac{2}{17\cdot19}+\frac{2}{19\cdot21}\right)\cdot462-y=19\)
dấu chấm thành dấu nhân nha thông cảm
Tìm x:a) ( frac{2}{11cdot13}+ frac{2}{13cdot15}+ .......... + frac{2}{19cdot21}) *462 - x 19b) x - frac{1}{2}- frac{1}{6}+ frac{1}{12}+ frac{1}{20}+ frac{1}{30}+ frac{1}{42} 1
Đọc tiếp
Tìm x:
a) ( \(\frac{2}{11\cdot13}\)+ \(\frac{2}{13\cdot15}\)+ .......... + \(\frac{2}{19\cdot21}\)) *462 - x = 19
b) x - \(\frac{1}{2}\)- \(\frac{1}{6}\)+ \(\frac{1}{12}\)+ \(\frac{1}{20}\)+ \(\frac{1}{30}\)+ \(\frac{1}{42}\)= 1
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
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a ) ta gọi biểu thức trước 462 là A
\(A=1.\left(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+...+\frac{1}{19}-\frac{1}{21}\right)\)
\(A=\frac{1}{11}-\frac{1}{21}=\frac{10}{231}\)
từ đó ta có biểu thức \(\frac{10}{231}.462-x=19\)\(\Rightarrow x=1\)
b)ta gọi biểu thức trước x là B
\(B=\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{6.7}\)
\(B=1-\frac{1}{7}=\frac{6}{7}\)
Từ đó x = \(\frac{1}{7}\)
kb nha
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Xem thêm câu trả lời
1. Tìm x biết: \(\left(\frac{2}{11\cdot13}+\frac{2}{13\cdot15}+......+\frac{2}{19\cdot21}\right)\cdot462-\left[2,04:\left(x+1,05\right)\right]:0,12=19\)
2. Cho a,b,c,d \(\ne\) 0 biết \(\frac{2a}{3b}=\frac{3b}{4c}=\frac{4c}{5d}=\frac{5d}{2a}\). Tính: \(C=\frac{2a}{3b}+\frac{3b}{4c}+\frac{4c}{5d}+\frac{5d}{2a}\)
Giúp mk với mấy bn ơi
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
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\(\frac{10}{231}\cdot623-24,808:\left(y+0,5\right)+12,04=30\)
Ai làm nhanh và đúng thì tớ tích
(10/231)x623 - 24,808/( y + 0,5 ) + 12,04 =30
=> 890/33 - 24,808:( y + 0,5 ) = 30 - 12,04
=> 24,808:( y + 0,5 ) = 890/33 - 449/25
=> y + 0,5 = 24,808 : ( 890/33 - 449/25 )
=> y = 2,253477734
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Tìm x thuộc N
\(x-\frac{20}{11\cdot13}-\frac{20}{13\cdot15}-\frac{20}{15\cdot17}-...-\frac{20}{53\cdot55}=\frac{3}{11}\)
\(x+\frac{2}{35}+\frac{2}{63}+...+\frac{2}{399}=\frac{2}{7}\)