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dễ mà
677x847+251/677x847+847-623
=677x847+251/677x847+224
=251/224
rồi tiếp theo nếu rút gọn dc thì bn tự rút gọn nhé nhớ chọn câu tra lời của mih nhs
\(\frac{677\cdot847+251}{678\cdot847-623}\)
\(=\)\(\frac{677\cdot847+251}{\left(677+1\right)\cdot847-623}\)
\(=\)\(\frac{677\cdot847+251}{677\cdot847+847-623}\)
\(=\)\(\frac{677\cdot847+251}{677\cdot847+224}\)
\(=\)\(\frac{251}{224}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{677\times874+251}{678\times874-623}\)\(=\frac{677\times874+251}{\left(677+1\right)\times874-623}\)\(=\frac{677\times874+251}{677\times874+1\times874-623}\)\(=\frac{677\times874+251}{677\times874+874-623}=\frac{677\times874+251}{677\times874+251}=1\)
\(\frac{677.874+251}{678.874-623}\)
\(=\frac{677.874+251}{\left(677+1\right).874-623}\)
\(=\frac{677.874+251}{677.874-1.874-623}\)
\(=\frac{677.874+251}{677.874+874-623}\)
\(=\frac{677.874+251}{677.874+251}\)
\(=1\)
Hok tốt
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\left(\frac{2}{11.13}+\frac{2}{13.15}+.........+\frac{2}{19.21}\right)x623-24,808:\left(y+0,5\right)+12,04=30\)
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
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
![](https://rs.olm.vn/images/avt/0.png?1311)
Quy đồng mẫu số:
37/67=25049/45359
377/677=25259/45359
Mà 25049/45359>25259/45359 nén 37/67>377/677
ta quy đồng
37/67 = 25049/45359
377/677 = 25259/45359
ta thấy 25049 < 25259 nên 37/67 < 377/677
![](https://rs.olm.vn/images/avt/0.png?1311)
=13/12x14/13x15/14x16/15x...x2006/2005x2007/2006x2008/2007
=2008/12
=502/3
A = 1\(\dfrac{1}{12}\) \(\times\) 1\(\dfrac{1}{13}\) \(\times\) 1\(\dfrac{1}{14}\) \(\times\) 1\(\dfrac{1}{15}\) \(\times\) ... \(\times\) 1\(\dfrac{1}{2005}\) \(\times\) 1\(\dfrac{1}{2006}\) \(\times\) 1\(\dfrac{1}{2007}\)
A = ( 1 + \(\dfrac{1}{12}\)) \(\times\) ( 1 + \(\dfrac{1}{13}\)) \(\times\) ( 1 + \(\dfrac{1}{14}\)) \(\times\)...\(\times\) ( 1 + \(\dfrac{1}{2006}\))\(\times\)(1+\(\dfrac{1}{2007}\))
A = \(\dfrac{13}{12}\) \(\times\) \(\dfrac{14}{13}\) \(\times\) \(\dfrac{15}{14}\) \(\times\) ...\(\times\) \(\dfrac{2007}{2006}\) \(\times\) \(\dfrac{2008}{2007}\)
A = \(\dfrac{13\times14\times15\times...\times2007}{13\times14\times15\times...\times2007}\) \(\times\) \(\dfrac{2008}{12}\)
A = 1 \(\times\) \(\dfrac{502}{3}\)
A = \(\dfrac{502}{3}\)
\(\dfrac{677.874+251}{678.874-623}\)
\(=\dfrac{677.874+251}{\left(677+1\right).874-623}\)
\(=\dfrac{677.874+251}{677.874+874-623}\)
\(=\dfrac{677.874+251}{677.874+251}\)
`=1`