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2/9 x a/b=5/6
=>a/b=5/6:2/8=5/6 x 9/2=45/12
3/7 : a/b=5/7
=>a/b=3/7:5/7=3/7 x 7/5=3/5
Day la cong thuc cua bai toan "Neu" a*b=\(\overline{ab}\)-a-b=10*a+b-a-b=9*a
a*b=54=9*a
suy ra a=54/9
a=6
a) \(\frac{6}{9}+\frac{5}{7}+\frac{1}{3}\)\(=\frac{2}{3}+\frac{5}{7}+\frac{1}{3}\)\(=\left(\frac{2}{3}+\frac{1}{3}\right)+\frac{5}{7}\)\(=1+\frac{5}{7}=\frac{12}{7}\)
b) \(\frac{17}{7}+\frac{6}{5}-\frac{20}{14}\)\(=\frac{17}{7}+\frac{6}{5}-\frac{10}{7}\)\(=\left(\frac{17}{7}-\frac{10}{7}\right)+\frac{6}{5}\)\(=1+\frac{6}{5}\)\(=\frac{11}{5}\)
c) \(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{72}\)\(=\frac{36}{72}+\frac{12}{72}+\frac{6}{72}+\frac{1}{72}=\frac{36+12+6+1}{72}=\frac{55}{72}\)
_Chúc bạn học tốt_
a) 6/9+5/7+1/3= 6/9+1/3+5/7=6/9+3/9+5/7=1+5/7=7/7+5/7=12/7
b)17/7+6/5-20/14=6/5+17/7-20/14=6/5+34/14-20/14=6/5+1=6/5+5/5=11/5
c)1/2+1/6+1/12+1/72=36/72+12/72+6/72+1/72=55/72
a/ (y+2/9):7/4=11/7
y+2/9=11/7.7/4
y+2/9=11/4
y=11/4-2/9
y=91/36
a)\(\frac{2}{3}\times\frac{4}{5}-\frac{3}{5}\times\frac{1}{2}=\frac{8}{15}-\frac{3}{10}\)
\(=\frac{7}{30}\)
b) \(\frac{12}{5}-\frac{4}{7}-\frac{3}{7}=\frac{64}{35}-\frac{3}{7}\)
\(=\frac{7}{5}\)
cho chj nhé em THKS em nhìu!
CHÚC EM HỌC TỐT!
=10969
10969
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