Question

a)  3/4 + 2/5 

b)  5/17 + 2/3 - 5/3 + 7/9 + 12/17

 

cứu tui , tui cảm ơn nhìu iu mọi người

 

Answer 1

b) 7/9

Answer 2

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

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

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

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

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

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

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

Answer 3

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

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

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

b,