Hãy tính hợp lí các phân số sau :a/ \(\frac{31}{23}\)- (\(\frac{7}{32}\)+\(\frac{8}{23}\))b/ (\(\frac{1}{3}\)+\(\frac{12}{67}\)+\(\frac{13}{41}\)) - (\(\frac{79}{67}\)- \(\frac{28}{41}\))c/ \(\frac{38}{45}\)- (\(\frac{8}{45}\)- \(\frac{17}{52}\)- \(\frac{3}{11}\))giúp mk nhanh với...
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Hãy tính hợp lí các phân số sau :
a/ \(\frac{31}{23}\)- (\(\frac{7}{32}\)+\(\frac{8}{23}\))
b/ (\(\frac{1}{3}\)+\(\frac{12}{67}\)+\(\frac{13}{41}\)) - (\(\frac{79}{67}\)- \(\frac{28}{41}\))
c/ \(\frac{38}{45}\)- (\(\frac{8}{45}\)- \(\frac{17}{52}\)- \(\frac{3}{11}\))
giúp mk nhanh với ^^
a) \(\frac{31}{23}-\left(\frac{7}{23}+\frac{8}{23}\right)\)
\(=\frac{31}{23}-\frac{15}{23}\)
\(=\frac{16}{23}\)
b) \(\left(\frac{1}{3}+\frac{12}{67}+\frac{13}{41}\right)-\left(\frac{79}{67}-\frac{28}{41}\right)\)
\(=\frac{1}{3}+\frac{12}{67}+\frac{13}{41}-\frac{79}{67}+\frac{28}{41}\)
\(=\frac{1}{3}+\left(\frac{12}{67}-\frac{79}{67}\right)+\left(\frac{13}{41}+\frac{28}{41}\right)\)
\(=\frac{1}{3}+\frac{-67}{67}+\frac{41}{41}\)
\(=\frac{1}{3}-1+1\)
\(=\frac{1}{3}\)
c) \(\frac{38}{45}-\left(\frac{8}{45}-\frac{17}{52}-\frac{3}{11}\right)\)
\(=\frac{38}{45}-\frac{8}{45}+\frac{17}{52}+\frac{3}{11}\)
\(=\frac{30}{45}+\frac{17}{52}+\frac{3}{11}\)
\(=\frac{2}{3}+\frac{17}{52}+\frac{3}{11}\)
\(=\frac{104+51}{156}+\frac{3}{11}\)
\(=\frac{155}{156}+\frac{3}{11}\)
\(=\frac{156}{156}-\frac{1}{156}+\frac{3}{11}\)
\(=1-\frac{1}{156}+\frac{3}{11}\)
\(=1-\left(\frac{11-468}{1716}\right)\)
\(=1-\frac{-457}{1716}\)
\(=1+\frac{457}{1716}\)
\(=\frac{2173}{1716}\)
a)31/23-(7/32+8/23)=31/23-7/32-8/23=(31/23-8/23)-7/32=1-7/32=25/32