a: =>x=2/3+7/3=3

b: \(\Leftrightarrow3x=\dfrac{9}{5}\cdot2=\dfrac{18}{5}\)

hay x=6/5

a: =>x=2/3+7/3=3

b: =>3x=18/5

hay x=6/5

a: =>x=2/3+7/3=3

b: =>3x=18/5

hay x=6/5  đúng ko

b) 7/9

\(\text{a)}\dfrac{3}{4}+\dfrac{2}{5}\)

\(=\dfrac{15}{20}+\dfrac{8}{20}=\dfrac{23}{20}\)

\(\text{b)}\dfrac{5}{17}+\dfrac{2}{3}-\dfrac{5}{3}+\dfrac{7}{9}+\dfrac{12}{17}\)

\(=\dfrac{5}{17}+\dfrac{2}{3}+\left(\dfrac{-5}{3}\right)+\dfrac{7}{9}+\dfrac{12}{17}\)

\(=\left(\dfrac{5}{17}+\dfrac{12}{17}\right)+\left[\dfrac{2}{3}+\left(\dfrac{-5}{3}\right)\right]+\dfrac{7}{9}\)

\(=1+\left(-1\right)+\dfrac{7}{9}\)

\(=0+\dfrac{7}{9}=\dfrac{7}{9}\)

\(a,\dfrac{3}{4}+\dfrac{2}{5}\)

\(=\dfrac{15}{20}+\dfrac{8}{20}\)

\(=\dfrac{23}{20}\)

b,

Nghĩa là cắt mảnh đất lm hai phần đúng ko , đợi mk nghĩ cho 

um ! kho ghe!!

Khó quá bạn ơi 

\(2^{54}=8^{18}< 9^{18}=3^{36}\)

Tên bạn hay......thế(-//.//-)

\(\text{Ta có:}2^{54}=\left(2^6\right)^9=64^9\)

\(3^{36}=\left(3^4\right)^9=81^9\)

\(\text{Mà }64^9< 81^9\)

\(\Rightarrow2^{54}< 3^{36}\)