Question

a)-2/5+7/21 

b)3/8+-5/6

giúp vs

Answer 1

a) `-2/5 + 7/21` `= -42/105 + 35/105` `= -1/15` b) `3/8 + (-5/6)` `= 9/24 + (-20/24)` `= -11/24`

Answer 2

a) -2/5 + 7/21

= -2/5 + 1/3

= -6/15 + 5/15

= -1/15

b) 3/8 + (-5/6)

= 9/24 + (-20/24)

= -11/24

Answer 3

a) \(\dfrac{-2}{5}+\dfrac{7}{21}=\dfrac{-42}{105}+\dfrac{35}{105}=\dfrac{-42+35}{105}=\dfrac{-7}{105}=\dfrac{-1}{15}\)

b) \(\dfrac{3}{8}+\dfrac{-5}{6}=\dfrac{9}{24}+\dfrac{-20}{24}=\dfrac{9+\left(-20\right)}{24}=\dfrac{-11}{24}\)