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\(A=21\frac{4}{11}-\left(1\frac{3}{5}+7\frac{4}{11}\right)\)
\(A=\frac{235}{11}-\left(\frac{8}{5}+\frac{81}{11}\right)\)
\(A=\left(\frac{235}{11}-\frac{81}{11}\right)+\frac{8}{5}\)
\(A=\frac{154}{11}+\frac{8}{5}\)
\(\Rightarrow A=\frac{78}{5}\)
\(B=\left(7\frac{8}{9}+2\frac{3}{13}\right)-\left(4\frac{8}{9}-7\frac{10}{13}\right)\)
\(B=\left(\frac{71}{9}+\frac{29}{13}\right)-\left(\frac{44}{9}-\frac{101}{13}\right)\)
\(B=\left(\frac{71}{9}-\frac{44}{9}\right)+\left(\frac{29}{13}-\frac{101}{13}\right)\)
\(B=\frac{27}{9}+\frac{-72}{13}\)
\(B=3+\frac{-72}{13}\)
\(\Rightarrow B=\frac{-33}{13}\)
P/s: Hoq chắc :v
a)\(\frac{-7}{25}.\frac{11}{13}+\frac{-7}{25}.\frac{2}{13}-\frac{18}{25}\)
\(=\frac{-7}{25}.\left(\frac{11}{13}+\frac{2}{13}\right)-\frac{18}{25}\)
\(=\frac{-7}{25}.1-\frac{18}{25}\)
\(=-\frac{7}{25}-\frac{18}{25}\)
\(=-1\)
b)\(\frac{5}{7}.\frac{1}{3}-\frac{5}{7}.\frac{1}{4}-\frac{5}{7}.\frac{1}{12}\)
\(=\frac{5}{7}.\left(\frac{1}{3}-\frac{1}{4}-\frac{1}{12}\right)\)
\(=\frac{5}{7}.\left(\frac{4}{12}-\frac{3}{12}-\frac{1}{12}\right)\)
\(=\frac{5}{7}.0\)
\(=0\)
a ) \(\frac{5}{7}.\frac{-7}{9}-\frac{5}{7}.\frac{2}{9}-\frac{5}{9}\)
\(\frac{3}{5}.\frac{8}{27}.\frac{5}{3}=1.\frac{8}{27}.1=\frac{8}{27}\)
\(\frac{7}{19}.\frac{1}{3}+\frac{7}{19}.\frac{2}{3}=\frac{7}{19}.\left(\frac{1}{3}+\frac{2}{3}\right)=\frac{7}{19}.1=\frac{7}{19}\)
\(\frac{12}{5}.4-4.\frac{7}{5}=4\left(\frac{12}{5}-\frac{7}{5}\right)=4.1=4\)
\(\frac{3}{5}x\frac{8}{27}x\frac{5}{3}\)
\(=\frac{3}{5}x\frac{5}{3}x\frac{8}{27}\)
\(=1x\frac{8}{27}\)
\(=\frac{8}{27}\)
\(\frac{7}{19}x\frac{1}{3}+\frac{7}{19}x\frac{2}{3}\)
\(=\frac{7}{19}x\left(\frac{1}{3}+\frac{2}{3}\right)\)
\(=\frac{7}{19}x1=\frac{7}{19}\)
\(\frac{12}{5}x4-4x\frac{7}{5}\)
\(=4x\left(\frac{12}{5}-\frac{7}{5}\right)\)
\(=4x1=4\)
Đúng luôn nên các bn nhớ k mk nhé
1/2+2/3+3/4+4/5+5/6+6/7+7/8+8/9+9/10x9/10
=9/10x(1/2+2/3)+(3/4+4/5)+(5/6+6/7)+(7/8+8/9)
=9/10x(1/3+3/5+5/7+7/9)
9/10x(1/3+3/5)+(5/7+7/9)
=9/10x1/5+5/9
9/50+5/9
=10
Bn Long làm đúng rồi bn 
nguyễn kim arica cứ làm theo cách đó là được .
Bn nào thấy đúng thì ủng hộ nha .
bạn ghép 1 với 3 ; 2 với 5
sau đó quy đồng là ra mà
ai trả lời đúng và nhanh thì mình k cho
\(\frac{3}{4}+\frac{2}{7}+\frac{1}{4}+\frac{3}{5}+\frac{5}{7}\)
=\(\frac{3}{4}+\frac{1}{4}+\frac{2}{7}+\frac{5}{7}+\frac{3}{5}\)
=\(\frac{4}{4}+\frac{7}{7}+\frac{3}{5}\)
=1+1 +\(\frac{3}{5}\)
= 2 + \(\frac{3}{5}\)
=\(\frac{13}{5}\)
=13/5
bạn nhóm các số cùng mẫu lại
\(\frac{3}{4}+\frac{2}{7}+\frac{1}{4}+\frac{3}{5}+\frac{5}{7}\)
\(=\left(\frac{3}{4}+\frac{3}{5}\right)+\left(\frac{2}{7}+\frac{5}{7}\right)+\frac{1}{4}\)
\(=\frac{27}{20}+1+\frac{1}{4}\)
\(=\frac{13}{5}\)
\(\left(\frac{3}{4}+\frac{1}{4}\right)+\left(\frac{2}{7}+\frac{5}{7}\right)+\frac{3}{5}\)= \(1+1+\frac{3}{5}\)= \(2+\frac{3}{5}\)=\(\frac{10}{5}+\frac{3}{5}\)= \(\frac{13}{5}\)
thank các bạn nhiều
\(\frac{3}{4}\)+ \(\frac{2}{7}\)+\(\frac{1}{4}\)+\(\frac{3}{5}\)+\(\frac{5}{7}\)
= \(\frac{3}{4}\)+ \(\frac{1}{4}\)+\(\frac{2}{7}\)+\(\frac{5}{7}\)+\(\frac{3}{5}\)
= 1+1+\(\frac{3}{5}\)
= 2+ \(\frac{3}{5}\)
= \(\frac{13}{5}\)