-5/2×(2/11+9/11)×(-5/7+15/7)

-5/2×1×10/7

-5/2×10/7

25/7

a,  -3/4 + 3/7 + -1/4 + 4/9 + 4/7

=\(\left(\frac{-3}{4}+\frac{-1}{4}\right)+\left(\frac{3}{7}+\frac{4}{7}\right)+\frac{4}{9}\)

=\(-1+1+\frac{4}{9}\)

=\(\frac{4}{9}\)

b, -7/9 x 4/11 + -7/9 x 7/11 + 5 và 7/9 

\(=\frac{7}{9}x\frac{-4}{11}+\frac{7}{9}x\frac{-7}{11}+5x\frac{7}{9}\)

\(=\frac{7}{9}x\left(\frac{-4}{11}+\frac{-7}{11}+5\right)\)

\(=\frac{7}{9}x4\)

\(=\frac{28}{9}\)

c, ( 21/31 + 2013/6039 ) - ( 44/53 - 10/31) - /53

A=-5/7x2/11+-5/7x9/11+1+5/7

A=5/7x-2/11+5/7x-9/11+1+5/7

A=5/7x[-2/11+-9/11+1]+1

A=5/7x0+1

A=0+1

A=1

lí luận rõ ra nhé

\(\left(\frac{2}{5}+\frac{7}{9}\right)+\frac{3}{5}\)

\(=\left(\frac{2}{5}+\frac{3}{5}\right)+\frac{7}{9}\)

\(=1+\frac{7}{9}=\frac{16}{9}\)

\(\frac{19}{11}+\left(\frac{8}{13}+\frac{3}{11}\right)\)

\(=\left(\frac{19}{11}+\frac{3}{11}\right)+\frac{8}{13}\)

\(=2+\frac{8}{13}=\frac{34}{13}\)

a) \(\left(\frac{2}{5}+\frac{7}{9}\right)+\frac{3}{5}\)  =  \(\left(\frac{2}{5}+\frac{3}{5}\right)+\frac{7}{9}\)=  \(1+\frac{7}{9}\)=\(\frac{16}{9}\).

b) Tương tự, bn tự làm đi nha.

z là gì vậy bn

?

a) = 1.1204
b) = 0.5714

a) = 1.1204
b) = 0.5714

25/7nha

giup minh voi

\(\frac{\frac{2}{5}-\frac{2}{9}+\frac{2}{11}}{\frac{7}{5}-\frac{7}{9}+\frac{7}{11}}:\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{\frac{7}{6}-\frac{7}{8}+\frac{7}{10}}\)

\(=\frac{2\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{11}\right)}{7\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{11}\right)}:\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{\frac{7}{2}\left(\frac{1}{3}-\frac{1}{4}+\frac{1}{5}\right)}\)

\(=\frac{2}{7}:\frac{1}{\frac{7}{2}}=\frac{2}{7}:\frac{2}{7}=1\)

.