Question

[Cô Thu Hà]

Thực hiện phép tính một cách hợp lí (nếu có thể):

a) $\dfrac{5}{9}-{{\Big(\dfrac{1}{3} \Big)}^{2}}$                   

b)$\dfrac{1}{5}. \dfrac{-3}{2}+\dfrac{-17}{2}. \dfrac{1}{5}$        

c) $1+\Big(\dfrac{-2}{5}+\dfrac{11}{13} \Big)-\Big(\dfrac{3}{5}-\dfrac{2}{13} \Big)$

Answer 1

[Tuyet]

`a) 5/9 - (1/3)^2= 5/9- 1/9= 4/9`

`b) 1/5. -3/2 + -17/2. 1/5= 1/5. (-3/2+-17/2)= 1/5.(-10)= -2`

`c) 1+ (-2/5 + 11/13) - (3/5- 2/13)= 1+ -2/5 + 11/13 + -3/5 + 2/13= 1+ (-2/5+ -3/5) +  (11/13+2/13) =1+ (-1)+1=1`