= 6 /14 = 3/7 nha bn 

\(\frac{11}{14}-\frac{5}{14}=\frac{11-5}{14}=\frac{6}{14}=\frac{3}{7}\)

Phải ko cô nương ? 

Ai nhanh được k nha :))

Trả lời 

\(A=\frac{11}{12+13}+\frac{12}{13+14}+\frac{1}{14+15}\)

Hay 

\(A=\frac{11}{12+13}+\frac{12}{13+14}+\frac{13}{14+15}\)

mong xem lại hộ cái 

\(\frac{3}{14}+\frac{2}{14}=\frac{5}{14}\)

\(\frac{3}{14}+\frac{2}{14}=\frac{3+2}{14}=\frac{5}{14}\)

\(\frac{14}{6}+\frac{1}{3}+\frac{14}{14}+\frac{14}{9}+\frac{7}{15}+\frac{6}{4}\)

\(=\frac{14}{6}+\frac{1}{3}+\frac{14}{9}+\frac{7}{15}+\frac{14}{14}+\frac{6}{4}\)

\(=\frac{42+6+28}{18}+\frac{7}{15}+\frac{2}{2}+\frac{3}{2}\)

\(=\frac{76}{18}+\frac{7}{15}+\frac{5}{2}\)

\(=\frac{76}{18}+\frac{5}{2}+\frac{7}{15}\)

\(=\frac{76+45}{18}+\frac{7}{15}\)

\(=\frac{121}{18}+\frac{7}{15}\)

\(=\frac{605+42}{90}\)

\(=\frac{647}{90}\)

\(\frac{14}{6}+\frac{1}{3}+\frac{14}{14}+\frac{14}{9}+\frac{7}{15}+\frac{6}{4}\)

\(=(\frac{7}{3}+\frac{1}{3})+1+(\frac{14}{9}+\frac{7}{15})+\frac{3}{2}\)

\(=\frac{8}{3}+1+\frac{91}{45}+\frac{3}{2}\)

\(=2+\frac{2}{3}+1+2+\frac{1}{45}+1+\frac{1}{2}\)

\(=\left(\frac{2}{3}+\frac{1}{45}+\frac{1}{2}\right)+\left(2+1+2+1\right)\)

\(=1+\frac{17}{90}+6\)

\(=7+\frac{17}{90}\)

\(=7\frac{17}{90}\)

DẤu nhân không phải x đâu nhe!

Cả hai đều sai 

\(=14:\left(\frac{14}{3}-\frac{14}{9}\right)+14:\left(\frac{2}{3}+\frac{8}{9}\right)\)

\(=14:\frac{28}{9}+14:\frac{14}{9}\)

\(=\frac{28}{9}+\frac{14}{9}\)

\(=\frac{42}{9}\)

\(14:\left(\frac{14}{3}-\frac{14}{9}\right)+14:\left(\frac{2}{3}+\frac{8}{9}\right)\)

\(=14:\left(\frac{42}{9}-\frac{14}{9}\right)+14:\left(\frac{6}{9}+\frac{8}{9}\right)\)

\(=14:\frac{28}{9}+14:\frac{14}{9}\)

\(=14.\frac{9}{28}+14.\frac{9}{14}\)

\(=14.\left(\frac{9}{28}+\frac{9}{14}\right)\)

\(=14.\left(\frac{9}{28}+\frac{18}{28}\right)\)

\(=14.\frac{27}{28}\)

\(=\frac{378}{28}\)

\(=\frac{27}{2}\)

= 14 : ( 14/3 - 14/9 ) + 14 : ( 2/3 + 8/9 ) 

= 14 : 28/9 +  14 : 14/9 

= 14 * 9/28 + 14 * 9/14 

= 14 * ( 9/28 + 9/14 ) 

= 14 * 27/28 

= 27/2 

Ta có:

A=\(14:\left(\frac{14}{3}-\frac{14}{5}\right)+14:\left(\frac{2}{3}+\frac{8}{9}\right)\)

\(=14:\left(\frac{14}{3}-\frac{14}{5}+\frac{2}{3}+\frac{8}{9}\right)\)

\(=14:\left(\frac{42+6+8}{3}-\frac{14}{5}\right)\)

\(=14:\left(\frac{56}{3}-\frac{14}{5}\right)\)

\(=14:\left(\frac{280-42}{15}\right)=14:\left(\frac{238}{15}\right)=14\cdot\frac{15}{238}=\frac{210}{238}\)

ko biết có tính sai chỗ nào ko

\(\frac{17}{14}>1\)