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(1/11-1/13+1/13-1/15+.....+1/19-1/21)*462-y=19
(1/11-1/21)*462-y=19
10/231*462-y=19
20-y=19
y=1
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\(\left(\frac{2}{11x13}+\frac{2}{13x15}+\frac{2}{15x17}+\frac{2}{17x19}+\frac{2}{19x21}\right)\)) x 462 - y = 19
\(=\left(\frac{13-11}{11x13}+\frac{15-13}{13x15}+\frac{17-15}{15x17}+\frac{19-17}{17x19}+\frac{21-19}{19x21}\right)\)x 462 - y = 19
\(=\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+\frac{1}{15}-\frac{1}{17}+\frac{1}{17}-\frac{1}{19}+\frac{1}{19}-\frac{1}{21}\)) x 462 - y = 19
\(=\left(\frac{1}{11}-\frac{1}{21}\right)\)x 462 - y = 19
\(=\left(\frac{21}{231}-\frac{11}{231}\right)\)x 462 - y = 19
\(=\frac{10}{231}\)x 462 - y = 19
\(=20\)- y = 19
y = 20 - 19
y = 1
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Nhưng bn ơiX là x^2 hay tách biệt nếu tách biệt thì là 9/49 còn nếu là x^2 thì là 3/7 nhé
\(=\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+...+\frac{1}{19}-\frac{1}{21}\right)xX=\frac{9}{7} \)\(=\left(\frac{1}{3}-\frac{1}{21}\right)xX=\frac{9}{7}\)\(=\frac{2}{7}xX=\frac{9}{7}\)
\(X=\frac{9}{7}:\frac{2}{7}\)
\(X=\frac{9}{2}\)
Tìm y biết \(\left(\frac{2}{11x13}+\frac{2}{13x15}+\frac{2}{15x17}+\frac{2}{17x19}\right)+462-y=19\)
![](https://rs.olm.vn/images/avt/0.png?1311)
ta lấy : (1/11-1/13+1/13-1/15+...+1/19)x462-y=19
(1/11-1/19)x462-y=19
32/209x462-y=19
70,73-y=19
y=70,73-19=51,73
đúng thì k cho mình nhé , ko đúng cũng ko sao ^^