a) \(\frac{1}{3}-\frac{3}{5}+\frac{5}{7}-\frac{7}{9}+\frac{9}{11}-\frac{11}{13}+\frac{13}{5}+\frac{11}{13}-\frac{9}{11}+\frac{7}{9}-\frac{5}{7}+\frac{3}{5}-\frac{1}{3}\)

=\(\left(\frac{1}{3}-\frac{1}{3}\right)+\left(\frac{5}{7}-\frac{5}{7}\right)+\left(\frac{7}{9}-\frac{7}{9}\right)+\left(\frac{11}{13}-\frac{11}{13}\right)+\frac{13}{5}\)

=\(\frac{0}{3}+\frac{0}{7}+\frac{0}{9}+\frac{0}{13}+\frac{13}{15}\)

=\(0+0+0+0+\frac{13}{5}\)

=\(\frac{13}{5}\)

\(\frac{1}{3}-\frac{3}{5}+\frac{5}{7}-\frac{7}{9}+\frac{9}{11}-\frac{11}{13}+\frac{13}{5}+\frac{11}{13}-\frac{9}{11}+\frac{7}{9}-\frac{5}{7}+\frac{3}{5}-\frac{1}{3}\)

\(=\left(\frac{1}{3}-\frac{1}{3}\right)+\left(\frac{-3}{5}+\frac{3}{5}\right)+\left(\frac{5}{7}-\frac{5}{7}\right)+\left(\frac{-7}{9}+\frac{7}{9}\right)+\left(\frac{-11}{13}+\frac{11}{13}\right)+\frac{13}{5}\)

\(=0+0+0+0+0+\frac{13}{5}\)

\(=\frac{13}{5}\)

Chúc bạn học tốt !

=(1/3-1/3)+(3/5-3/5)+(5/7-5/7)+(7/9-7/9)+(9/11-9/11)+(11/13-11/13)+13/5

=0+0+0+0+0+0+13/5

=13/5

\(\frac{3}{8}+\frac{4}{5}=\frac{15}{40}+\frac{32}{40}=\frac{47}{40}\)

47/40 bn nhé

kbn nha

\(\frac{3}{8}\)+ \(\frac{4}{5}\)= \(\frac{15}{40}\)+ \(\frac{32}{40}\)= \(\frac{47}{40}\)

a)   \(x-\frac{4}{5}=\frac{5}{7}\)

                  \(x=\frac{5}{7}+\frac{4}{5}=\frac{53}{35}\)

b)   \(5x=-\frac{1}{5}\)

        \(x=-\frac{1}{5}:5=-\frac{1}{25}\)

c)   \(\frac{5}{3}-x=7+\frac{4}{5}\)

      \(\frac{5}{3}-x=\frac{39}{5}\)

                  \(x=\frac{5}{3}-\frac{39}{5}=-\frac{92}{15}\)

d)    \(-\frac{5}{11}+2x=\frac{7}{22}\)

                        \(2x=\frac{7}{22}+\frac{5}{11}\)

                        \(2x=\frac{17}{22}\)

                          \(x=\frac{17}{22}:2\)

                           \(x=\frac{17}{44}\)

       \(x=-\frac{1}{5}:5\)

NÈ BẠN!!!

a) \(x-\frac{4}{5}=\frac{5}{7}\)

\(x=\frac{5}{7}+\frac{4}{5}=\frac{25}{35}+\frac{28}{35}=\frac{53}{35}\)

b) \(5x=-\frac{1}{5}+\frac{11}{5}\)

\(5x=2\)

\(x=\frac{2}{5}\)

c)\(\frac{5}{3}-x=7\)

\(x=\frac{5}{3}-7=\frac{5}{3}-\frac{21}{3}=-\frac{16}{3}\)

d) \(-\frac{5}{11}+2x=\frac{7}{22}\)

\(2x=\frac{7}{22}-\frac{-5}{11}=\frac{7}{22}-\frac{-10}{22}=\frac{17}{22}\)

\(x=\frac{17}{22}:2=\frac{17}{22}\cdot\frac{1}{2}=\frac{17}{44}\)

K CHO MÌNH NHA!!!

\(a,\frac{21}{36}.\frac{5}{2}-\frac{7}{12}.\frac{2}{7}+\left(2018-2019\right)^0\)

=\(\frac{7}{12}.\frac{5}{2}-\frac{7}{12}.\frac{2}{7}+\left(-1\right)\)

= \(\frac{7}{12}.\left(\frac{5}{2}+\frac{2}{7}\right)+\left(-1\right)\)

=\(\frac{7}{12}.\frac{39}{14}+\left(-1\right)\)

=\(\frac{13}{8}+\left(-1\right)\)

= \(\frac{5}{8}\)

\(b,-12\frac{1}{3}-\frac{5}{7}+7\frac{1}{3}+1\frac{5}{7}+1^{2019}\)

=\(-\frac{37}{3}+\frac{-5}{7}+\frac{22}{3}+\frac{12}{7}+1\)

=\(\left(\frac{-37+22}{3}\right)+\left(\frac{-5+12}{7}\right)+=1\)

= \(-5+1+1\)

=\(-3\)

làm gì đây????

a. Giá trị nhỏ nhất của A=\(\sqrt{2}+\frac{3}{11}\)

không có giá trị lớn nhất

b. Giá trị lớn  nhất của B là \(\frac{5}{7}\) khi x=5 không có GTLN

dùng phần mềm viết không chuẩn do chưa quen

GTNN của A là 3/11 khi x=-2

GTLN của B la 5/7 khi x=-5 

\(\frac{\left|x-5\right|}{3}-\frac{1}{2}=\frac{1}{3}\)

\(\frac{\left|x-5\right|}{3}=\frac{1}{3}+\frac{1}{2}\)

\(\frac{\left|x-5\right|}{3}=\frac{5}{6}\)

\(\left|x-5\right|=5:\left(6:3\right)\)

\(\left|x-5\right|=2,5\)

\(x=2,5+5\)

\(x=7,5\)

\(\frac{\left|x-5\right|}{3}-\frac{1}{2}=\frac{1}{3}.\)

\(=>\frac{\left|x-5\right|}{3}=\frac{5}{6}\)

\(=>\left|x-5\right|=\frac{15}{6}\)

\(=>\left|x-5\right|=\frac{5}{2}\)

\(\left(+\right)x-5=\frac{5}{2}=>x=\frac{5}{2}+5=\frac{15}{2}\)

\(\left(+\right)x-5=-\frac{5}{2}=>x=5-\frac{5}{2}=\frac{5}{2}\)

Vậy \(x=\frac{5}{2};x=\frac{15}{2}\)

Kết quả minh xem xét thì đúng là x= 5/2 và -15/2