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20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.201520152015.2016 + 20162016.2015
B(40)={0;40;80;120;160;200;240;280;320;360;...}
B(45)={0;45;90;135;180;225;270;315;360;..}
=> BCNN(40,45)=360
Ta có: 40=2³.5
45=5.3²
=>BCNN(40;45)Là 2³.9.5=180
Vậy BCNN(40;45)=180
\(a,\dfrac{-3}{5}+\dfrac{7}{21}+\dfrac{-4}{5}+\dfrac{7}{5}\)
\(=\left(\dfrac{-3}{5}+\dfrac{7}{5}\right)+\dfrac{7}{21}+-\dfrac{4}{5}\)
\(=\dfrac{4}{5}+\dfrac{7}{21}+-\dfrac{4}{5}\)
\(=\left(\dfrac{4}{5}+\dfrac{-4}{5}\right)+\dfrac{7}{21}\)
\(=0+\dfrac{7}{21}=\dfrac{7}{21}\)
\(b,\dfrac{-3}{17}+\left(\dfrac{2}{3}+\dfrac{3}{17}\right)\)
\(=-\dfrac{3}{17}+\dfrac{2}{3}+\dfrac{3}{17}\)
\(=\left(\dfrac{-3}{17}+\dfrac{3}{17}\right)+\dfrac{2}{3}\)
\(=0+\dfrac{2}{3}=\dfrac{2}{3}\)
\(c,\dfrac{-5}{21}+\left(\dfrac{-16}{21}+1\right)\)
\(=\dfrac{-5}{21}+\dfrac{-16}{21}+1\)
\(=\dfrac{-21}{21}+1\)
\(=\left(-1\right)+1=0\)
Tick mình nha ^^
a.\(\dfrac{-3}{5}\)+\(\dfrac{7}{21}\)+\(\dfrac{-4}{5}\)+\(\dfrac{7}{5}\)= (\(\dfrac{-3}{5}\)+\(\dfrac{-4}{5}\)+\(\dfrac{7}{5}\)) + \(\dfrac{7}{21}\)=0+\(\dfrac{7}{21}\)=\(\dfrac{7}{21}\)
b.\(\dfrac{-3}{17}\)+(\(\dfrac{2}{3}\)+\(\dfrac{3}{17}\))= \(\dfrac{-3}{17}\)+\(\dfrac{3}{17}\)+\(\dfrac{2}{3}\)=0+\(\dfrac{2}{3}\)=\(\dfrac{2}{3}\)
c.\(\dfrac{-5}{21}\)+(\(\dfrac{-16}{21}\)+1)=\(\dfrac{-5}{21}\)+\(\dfrac{-16}{21}\)+1=(-1)+ 1 = 0
Ủa nhớ nãy giải rồi mà ta?
Thôi giải lại kĩ hơn:
= 32 - ( - 672 ) + 240
= 32 + 672 + 240
= 944
\(\frac{x}{27}\)= \(\frac{-2}{3,6}\)
\(\Leftrightarrow\)\(x\cdot3,6=27\cdot-2\)
\(\Leftrightarrow\)\(x\cdot3,6=-54\)
\(\Leftrightarrow\)\(x=-\frac{54}{3,6}\)
\(\Rightarrow\)\(x=-15\)
\(20152015.2016-20162016.2015\)
\(\text{=}10001.2015.2016-10001.2016.2015\)
\(\text{=}10001.\left(2015.2016-2016.2015\right)\)
\(\text{=}10001.0\)
\(\text{=}0\)